
GlassjQ-Ilaii- 
BookJl:L 



?3a. 



ELEMENTS 

CHEMISTRY. 

IN WHICH THl 

RECENT DISCOVERIES IN THE SCIENCE ARE INCLUDED 

AND ITS 

DOCTRINES FAMILIARLY EXPLAINED. 

ILLUSTRATED BY NUMEROUS ENQRAVINCS, 
AND 

DESIGNED FOR THE USE OF SCITOOLS AND ACADEMIES. 



BY J; L. COMSTOCK, M. D. 

KBM. CON. M. S. ; no . MEM. R. 1. M. S. ; AUTHOR 07 NOTES TO CONV. ON CHEMISTBT 

AUTHOR OF GRAM. OF CHEMISTRY; KLEM. MINERALOGY; NATURAL HISTORY 

OF QUADRUPEDS AND BIRDS ; NATURAL PHILOSOPHY, ETC. 



fox; TY- FOURTH EDITION FROM THE FIFTY.FOURTH. 



NEW YORK: 
PUBLISHED BY PRATT, WOODFORD & CO. 

1852. 






Entered according to Act of Congress, in the year 184G, 

By D. F. Robinson. 

la the Clerk's Office of the District Court of the District of Connecticut. 



PRINTED BT 

CASE, TIFFANY, AND CO. 

HARTFORD, CONN. 



STEREOTYPED BY 

CHARD H. HOBBS 

HARTFORD, CONN. 



ADVERTISEMENT. 



New stereotype plates being required for this work, the 
duthor has not neglected the opportunity of making such 
alterations in the text as it seemed to require. He has 
therefore re-written, altered, changed, and revised, a large 
portion of the matter, adding new cuts when required, 
so that it is thought neither the teacher, nor his pupil will 
complain of it, as not possessing claims to be placec 
among the books of its kind written at the present day. 
The new substances, so far as an account of them could 
be had from the most recent publications, have been added, 
and the new terms, when it was thought they would not 
too severely tax the memory of the teacher, and his pupils, 
have been employed. 

It is hoped, therefore, that the public will think with the 
Author, that the book is much more worthy of general 
patronage than heretofore. 



Hartford, Conn. 



PREFACE. 



[t is hardly necessary for the author of the following 
volume to make any excuses for its publication, since, not- 
withstanding the multiplicity of books on the same sub- 
ject, there seems to be none, which are exactly adapted to 
the object for which this is principally designed. The 
Conversations on Chemistry, and the works of Parke and 
Joyce, besides the interlocutory form in which they are 
written, are objectionable, in not containing the recent dis- 
coveries and improvements in the science ; and the volume 
of Dr. Turner, though free from these objections, is too 
large for the use of schools and academies. 

In this volume, it has been the intention of the author, 
not only to avoid these objections, but, at the same time, to 
explain the elements and doctrines of the science in suffi- 
cient detail, to give a competent knowledge of its several 
parts, and in such language as can be understood by those 
who will but read the book attentively, and pursue the 
subject in course. 

It appears to the writer, that in teaching Chemistry to 
youth, its elementary parts have not been sufficiently in 



VI PREFACE. 

sisted on at the beginning. Of all the sciences, this is the 
most complete, in respect to its language, the order of its 
arrangement, the succession of its subjects, and conse- 
quently, in the facility with which it may be learned. But 
from these perfections, arises the absolute necessity of be- 
coming well acquainted with its first principles, before the 
student can derive and retain any useful knowledge from 
its study. The nomenclature of chemistry, the laws of 
affinity, and the doctrine of proportions, are far more neces- 
sary to a proper knowledge of this science, than is a know- 
ledge of mathematics to the study of Astronomj^ The 
cause of an eclipse, or the reason why the complicated 
motions of the earth should produce a change, of seasons, 
can be fully understood without the use of mathematics. 
But without a knowledge of affinity, and proportions, the 
decomposition of a salt, or the formation of a definite com- 
pound, are absolutely incomprehensible phenomena ; nor 
can they be explained without a previous acquaintance 
with the peculiar language of chemistry. 

It is from a conviction of the importance of first princi- 
ples in learning this science, that the author has devoted 
so much attention to the imponderable agents, attraction, 
affinity, and galvanism, and to the explanation of definite 
proportions and chemical equivalents. 

The doctrine of definite proportions, being now univer- 
sally adopted, forms one of the fundamental principles of 
chemical science. And whether the theory of atoms, 
which accounts for the facts on which this doctrine is 
founded, be true, or folse, the doctrine itself will ever main- 
tain its integrity, its elements being nothing more than the 
expression of facts which experiment and analysis have 
developed. The subject of proportions, independently o( 
its relation to the theory or practice of Chemistry, is highly 
curious, and of uncommon interest, both to the naturalist 



pREFACi^. vii 

and tho moral philosopher. To the first it shows, that the 
laws of nature are equally inherent and efficient, in dead 
and in animated matter, and that the effects of these laws 
are as pecuhar and distinctive in the formation of chemicai 
compounds, as they are in the production and habitudes of 
the different races of animals. To the moralist, this sub- 
ject teaches, that nothing has been formed by the fortuitous 
concurrence of atoms, but that even the "stocks and 
stones " bear the impress of creative agency and design — 
that the air he breathes, and the water he drinks, are 
formed of invariable proportions of certain elements, and 
that these compounds are so precisely adapted to his nature 
and wants, that the least change in the proportion of their 
constituents would inevitably effect his destruction. 

Besides the charms which this subject presents to tho 
reflecting student, the composition of compound bodies, in 
recent books of chemistry, is expressed in equivalent num- 
bers, and therefore cannot be understood without a know- 
ledge of the doctrine of proportions. The author, there- 
fore, before the description of each element and compound, 
has affixed to its name, at the head of the sections, its 
combining number, or atomic weight. By this arrange- 
ment, the pupil, at a single glance, becomes acquainted, 
not only with the scientific, and common names, but also 
with the composition and proportions of all the compounds 
described. 

In respect to the authorities which have been consulted 
in the composition of this work, the principal are, Dr 
Thomson, Dr. Henry, Sir H. Davy, Mr. Gray, Dr. Ure, 
Mr. Accum, Mr. Faraday, the Library of Useful Know- 
ledge, the Journal of the Eoyal Institution, Silliman's 
Journal, and Dr. Turner. 

Of the work of the latter author, free use has been 
made, his arrangement of subjects, with some variations, 



Viii PREFACE. 

having been adopted, and his exposition of the doctrine of 
proportions carefully consulted. The work now offered, 
is not, however, to be considered as a servile compilation ; 
the former experience of the author as a lecturer, and his 
habit, for many years, of analysing various substances, 
having given him opportunities, not only of verifying the 
deductions of others, but occasionally of making new ex- 
periments for himself 

Hartfordj Conn. 



CHEMISTRY. 



1. Cheivhstry is that science which investigates the 
composition and properties of bodies, and bj which we are 
enabled to explain the causes of the natural changes 
which take place in material substances. 

Natural Science has been divided into two great branch- 
es, the one comprehending all those natural changes which 
are accompanied by sensible motions ; the other including 
all those natural changes accompanied by insensible mo- 
tions. The first science is called Natural Philosophy ; in- 
cluding also the Philosophy of Mechanics, and the laws 
of motion. The second is known under the name of 
Chemistry, or Chemical Philosophy. 

As a science. Chemistry is of the highest importance to 
mankind, since, by its investigations, the practical arts are 
constantly improving. 

All chemical knowledge is founded on analysis and syn- 
thesis^ that is, the decomposition of bodies, or the separation 
of compounds into their simple elements, or the recomposi- 
tion of simple bodies into compounds. 

When water is passed through a red hot iron tube, in the 
form of steam, it is decomposed ; its oxygen uniting with the 
iron, while its hydrogen passes away in a state of freedom, 
or may be collected and retained. This is called analysis ; 
and the bodies so separated from each other, if they cannot 
again be decomposed, are called elements. Thus hydrogen 
and oxygen are the elements of water. When oxygen, 
which may be obtained pure, as will be seen in another 
place, is burned with hydrogen, a quantity of water will 
be formed. This is called synthesis^ or the recomposition 



What is Chemistry ? How is science divided ? What is the foundation of 
all chemical knowledge ? What is analysis ? What is synthesis ? 
1* 



10 IMPONDERABLE AGENTS. 

of water from its elements. Thus, all knowledge of this 
science is obtained by experiment. 

As a science, chemistry is intim.ately connected with a 
great variety of natural phenomena. All satisfactory ex- 
planation of the causes of rain, hail, dew, wind, earth- 
quakes, and volcanoes, have been given by the aid of 
chemical knowledge. The phenomena of respiration, the 
decay and growth of plants, and the functions of the se- 
veral parts of animals, are also explained in a satisfactory 
manner, only by the aid of chemistry. 

As an art, chemistry is connected, more or less intimately 
with nearly every branch of human industry, and particu- 
larly with agriculture and manufactures. In its applica- 
tion to agriculture, chemistry furnishes the most direct and 
certain means of ascertaining what a baiTen soil wants to 
make it a fruitful one, and also what ingredient any soil 
requires to best adapt it to any given kind of produce. 
Many of our most common and useful articles are manu- 
factured entirely by chemical processes. The making of 
soap, glass, bleaching salts, the several kinds of acids, and 
almost every kind of medicine, depend wholly on the 
manipulations of chemistry. The art of the potter, iron- 
smith, tanner, sugar-maker, distiller, brewer, vintner, paper- 
maker, and painter, are also connected in various degrees 
with chemistry. 

Natural objects may be separated into two great di- 
visions, or classes, viz. : Imponderable agents and Ponder- 
able bodies. 



PART L 

IMPONDERABLE AGENTS. 

2. The imponderable agents are Light, Caloric, or Heat,, 
Electricity, and Galvanism. These are called the impon- 
derable agents, because they possess no appreciable weight. 

What are among the natural phenomena which chemistry explains? What 
are among the most important arts which derive advantage from chemistry? 
How are natural objects divided ? What are the imponderable agents ? Why 
we these agents called imponderable f 



CALOltlC. \ J 

The investigation of many of the properties of these agents, 
and particular!}^ those of hght and attraction, belong to the 
several departments of Natural Philosophy, but they each 
possess properties also, which are strictly chemical, and it 
is these properties only, which it is proposed here to ex- 
amine. 

CALORIC. 

3. Heat is the sensation w^hich one feels w^hen he 
touches a body hotter than the hand ; and this sensation is 
caused by the passage of caloric from the hot body to the 
hand. Thus caloric is the cause of the sensation which 
we call heat, and heat is the effect of the passage of ca- 
loric into the hand. Caloric, then, is the matter or principle 
of heat, while heat is the sensation produced by the trans- 
fer of this principle to the hving system, from some body 
hotter than itself 

Caloric is imponderable ; that is, there is no appreciable 
difference in the weight of a body, whether it is hot or 
cold. 

This principle seems to be present in all bodies, nor is 
there any known process by w^hich it can be separated 
from any substance. For, since heat constantly passes 
from the hotter to the colder body, until every thing in the 
same vicinity becomes of an equal temperature, so if we 
take a substance at a temperature however low, and carry 
it to a place where the temperature is still lower, this sub- 
stance will give out heat until its temperature becomes the 
same with that of the surrounding air. For instance, if a 
piece of ice at 32 degrees of temperature, could be trans- 
ported to any place, as in Siberia, where the temperature is 
60 degrees below 32, then this piece of ice will continue to 
emit caloric until its temperature becomes only equal to 
that of the surrounding atmosphere, and it would therefore 
give out 60 degrees of heat. It will be quite obvious to 
any one, that if a piece of iron, or any other substance, be 
carried from the open air on a summer's day, where the 
heat is 92, to an ice house, where the heat is only 32, that 
the iron will continue to part with its heat until it becomes 

When one touches a body hotter than his hand, why does he feel the sen 
sation of heat ? What is caloric ? What is heat ? How is it proved that 
caloric is imponderable ? How is it shown that caloric is present in all 
bodies ? What illustrations show that ice will emit caloric ? How are heat 
and cold relative terms ? How is it shown that the sensation of cold often 
depends on the conducting power of the body ? 



12 (-ALOKIC. 

of tlie same temperature with the ice, and therefore that it 
wiil, in a short time, lose 60 degrees of heat, as indicated 
bj the thermometer. 

4. Heat and cold are therefore merely relative terms, 
and so far as our sensations are concerned, depend on cir- 
cumstances. Thus we call a body cold when its tempera- 
ture is lower than our own, and it has at the same time, 
the power of conducting heat rapidly. That the sensation 
of cold, which we experience, when touching another body 
with the hand, depends greatly on the conducting power of 
the body touched, is easily proved by the following experi- 
ment. A piece of woollen cloth, or fur, and a vessel of 
quicksilver, being placed in the same room, will both indi- 
cate the same temperature when the bulb of a thermometer 
is wrapped in the one, or plunged into the other. And yet, 
if the experiment be made in the warmest day of summer, 
the mercury will feel cold to the hand, while no such sen- 
sation will be produced on touching the cloth or fur. Now 
both articles touched being of the same temperature, it is 
certain that the different sensations must depend on the 
power of the mercury to absorb, or conduct away, the heat 
of the hand more rapidly than the fur or cloth. 

5. On the contrary, we say a body is wann, or hot, 
when it imparts heat to the hand, more or less rapidly. 
But this sensation, to a certain degree, also depends on cir- 
cumstances, and is connected with the relative temperature 
of the hand, and the conducting power of the substance 
touched. Thus, if one hand be placed in water, at 32 
degrees, and the other in water at 130 degrees, and then 
both hands be plunged into water at 90 degrees, one hand 
will feel cold, and the other waim, though the temperature 
to which both are exposed is the same. This principle is 
illustrated by the different sensations which men and ani- 
mals experience, when transported from a cold or hot cli- 
mate to one which is temperate. A Russian would con- 
sider the coldest New England winter a pleasant and com- 
fortable season, while an inhabitant of Sumatra, or Borneo, 
would tremble with the cold of our September. A white 
bear from Greenland, or a dog from Kamtschatka, would 

When do we say a body is warm or hot ? How is it shown that the sen- 
sations of heat and cold depend on circumstances ? Wliat illustrations are 
given of this principle? What is one of the most obvious properties of 
caloric? What is meant by equilibrium? How is it shown that caloric 
tends to an equilibrium ? 



CALORIC. 13 

constantly suffer from the heat, while an elephant, or a na- 
ked dog- from Africa, would require protection from the cold. 
G. Equilibrium of Caloric — One of the most obvious 
properties of caloric is, its tendency to an equilibrium^ that 
is, its disposition to pass from the hotter body to that which 
is colder. Thus, if several bodies of different temperatures 
be placed in the same room, the warmer body will continue 
to impart its heat to those which are colder until they all 
indicate the same temperature by the thermometer. This 
distribution is so equal and general, that two thermometers, 
graduated exactly alike, and placed under the same cir- 
cumstances in the open air, will indicate the same degrees 
of heat though placed miles apart. Thus, caloric has the 
power of pervading all substances, and of equalizing their 
temperatures. 

7. Free Caloric. — Caloric exists in two different states, 
viz. in a state of combination .^ and in a state oi freedom. It 
has already been stated, that all bodies are supposed to 
contain caloric, but that all bodies do not contain sensible 
heat, or, are not warm to the touch, requires no proof 
Common occurrences, however, as we have already seen, 
are sufficient to show, that, to a certain extent, the sensa- 
tion of heat depends on circumstances, and that it is only 
necessary that the body touched should be of a highei 
temperature than the hand, for us to perceive the sensation 
of warmth. But it by no means proves, that because the 
thing touched does not feel warm, that it contains no ca- 
loric. It follows, therefore, that when, the body touched, 
conveys the sensation of heat, that caloric passes from the 
body to the hand, and this is called /ree, or uncombined 
caloric ] but that when no sensation follows, the heat is 
combined.^ or latent.^ in the body touched, and therefore is 
not imparted to the hand. 

Combined or latent Caloric. — This is also sometimes called 
caloric of fluidity., because, in the conversion of solids into 
fluids, a quantity of heat is absorbed which is not indicated 
by the thermometer, and v/hich, therefore, becomes latent 
in the fluid. 

8. The experiments of Dr. Black, in relation to this sub- 
ject, are highly curious and interesting. These experi- 

What conclusion is drawn from the fact ttiat caloric is equally distributed? 
What are the two states in which caloric exists? Is it a proof that a body 
contains no heat because it does not feel wa;m ? If every body contains heat,- 
why does it not always feel warm ? What is free heat? What is latent heat? 

2 



14 CALORIC. 

ments prove, that if a pound of water, at 32 degreey, be 
mixed with a pound of water at 172 degrees, the temper- 
ature of the mixture will be intermediate between them, and 
therefore 102 degrees. But if a pound of ice at 32 degrees 
be mixed with a pound of water at 172 degrees, the ice will 
soon be dissolved, and then, on cipplying the thermometer 
to the water thus formed, it will be found at the same tem- 
perature that the ice was before the addition of the warm 
water, and therefore at 32 degrees, instead of 102 degrees, 
as before. In this experiment, therefore, the pound of hoi 
water lost 140 degrees of caloric, which is emploj^ed in 
melting the ice, and which is not appreciable by the ther- 
mometer, but remains latent in the water. It follows, then, 
that a quantity of caloric becomes insensible during the 
melting of ice, which, were it free, or uncombined, would 
raise the temperature of the same weight of water 140 
degrees : for, the ice being at 32 degrees, and the water at 
172 degrees, at the beginning of the experiment, and the 
whole being at 32 degrees at the end, the water loses 140 
degrees, being the excess of 172 degrees above 32. 

9. It is well known, that if a piece of ice be exposed to 
the raj^s of the hottest sun in the summer, or if it is placed 
in a vessel over a fire, the temperature of the ice, or of the 
water flowing from it, will not be raised above 32 degrees, 
until the ice is all melted, when the thermometer placed in 
the vessel ^vill instantly begin to rise. Those who have 
melted snow, or ice, for culinary or other pui-poses, are well 
aware how much more tim.e and fuel it takes to obtain a 
vessel of boiling water from ice, than it does fromx tjie liquid 
itself But this fact is readily accounted for by Dr. Black's 
experiment, since we have seen above, that 140 degrees of 
heat are first emploj^ed merely in converting the ice into 
water, and that this caloric does not raise the water one 
degree a'^ove the freezing point, or 32 degrees, until all the 
ice is mi 'ed. 

10. T 's principle is of vast consequence to the world, 
and part ularly to the inhabitants of cold climates, where 
the grou..J is covered with snow and ice, a part or the 
whole of the year. In some northern climates, and par- 



How man}- degrees of heat become latent during the conversion of ice 
into water ? How is this shown b}' experiment ? What common fact shows 
that the temDcniture of water cannot be raised as long as it contains ice ? 
What circumstances are mentioned under which the great quantity of caloric 
absorbed by melting ice, is a blessing to mankind ? 



.STEAM. [5 

uoula fly in Russia, the transition from the cold of winter to 
the heat of summer takes place within a few days, the 
ground being covered several feet deep with the accumu- 
lated snow of the winter. Now, were it not for the fact 
above explained, and did the snow and ice follow the same 
law, in respect to temperature, that we observe in some 
other bodies, this whole mass would be turned into water 
nearly as soon as the temperature of the atmosphere be- 
came above 32 degrees, and consequently the whole coun- 
try would be inundated and destroyed by the flood. 

But in consequence of the quantity of caloric employed 
in the liquefaction of the snow, the melting is gradual, and 
no such accident ensues. This is a striking instance of 
the wisdom and mercy of Providence towards man, though 
to most of the world it is unseen and unknown. 

We have mentioned the melting of ice, as being the 
most famihar example, in most parts of our country, of the 
conversion of a solid into a fluid. But the principle holds 
with respect to the conversion of other solids into liquids, 
though the quantity of caloric required for this purpose 
varies with the substance. 

From the experiments of Dr. Irvine, it appears that the 
following named substances vary in this respect very 
widely, and also very unexpectedly. Equal weights of 
each substance are supposed to be employed in the experi- 
ments : The degrees indicate the extent to which each 
would have been heated by the caloric of fluidity proper 
to it. Spermaceti 145 degrees; lead 162 deg. ; bees-wax 
175 deg. : zinc 493 deg. ; tin 500 deg. ; bismuth 550 deg. 



11. When water, or other liquids, are converted into 
steam, a large quantity of caloric is absorbed, which is not 
indicated by the thermometer, and which, therefore, be- 
comes latent in the steam. 

If a thermometer be placed in an open vessel of water, 
over a fire, there will be indicated a gradual increase of 
heat until the water boils, after which no increase of the 
fire will raise the temperature of the water another degree ; 

When the temperature of the atmosphere is above the freezing point, why 
does not the snow and ice instantl)' return to water? In melting, do other 
solids besides ice absorb a quantity of caloric not appreciable by the ther- 
mometer ? Why cannot water, in an open vessel, be heated higher than 212 
degrees ? 



16 STEAM. 

nor does the steam, arising from a vessel of water wiiich 
boils violently, indicate a greater degree of heat than the 
water itself, or of the steam arising from another vessel 
which boils moderately. The steam convej^s away all the 
heat above 212 degrees of Fahrenheit's thermometer, which 
is the temperature of boihng v/ater under the ordinary pres- 
sure of the atmosphere. 

The quantity of caloric which combines with the water 
to forai steam, is nearly 1 000 degrees greater than that of 
the same weight of boiling water. In other terms, the 
caloric of fluidity in steam surpasses that of an equal 
weight of boihng water by nearly 1000 degrees. Conse- 
quently, there is nearly 1000 degrees of heat in steam 
which is not indicated by the thermometer, and is therefore 
latent. 

12. Latent heat in Steam. — Various methods have been 
adopted by different philosophers in order to ascertain cor- 
rectly the exact quantity of latent heat in steam. Among 
these, one of the latest and most simple is that of Dr. Ure, 
of Glasgow. His apparatus consisted of a small glass 
retort, with a short neck, inserted into a globular receiver 
of the same material, made very thin, and about three 
inches in diameter. This globe was surrounded with a 
certain quantity of water, at a known temperature, in a 
glass basin. A quantity of water, or other liquid to be ex- 
amined, amounting to 200 grains, was put into the retort, 
and rapidly distilled into the globe, by the heat of an Ar- 
gand lamp. The heat imparted by the condensation of the 
steam in the globe, to the water contained in the dish, by 
which it was surrounded, was indicated by a very delicate 
thermometer, kept constantly moving through it. By 
means of this contrivance. Dr. Ure found the latent heat 
of the steam of water to be 1000 degrees. That of alco- 
hol, of the sp. grav. 825, to be 457, and that of ether about 
303. 

13. Cause of Ebullition. — We have stated that the tem- 
perature of boihng water, and of steam, is 212 degrees, 
under the ordinary pressure of the atmosphere. The cause 
of ebullition, or boiling, is the formation of vapour, or 
steam, at the bottom of the vessel, in consequence of the 



How many degrees of heat does steam contain, which is not indicated hj 
the thermometer? Describe the apparatus of Dr. Ure, to ascertain the quan 
tity of caloric in steam ? What is the cause of /ebullition or boiling? 



STEAM. 17 

application of heat there. The steam being lighter than 
the water, or other fluid from which it is made, constantly 
ascends in bubbles, and escapes from the surface into the 
open air. The process of boiling, when conducted in a tall 
glass vessel, over an Argand lamp, may be minutely ex- 
amined, and is both interesting and instructive. 

It is found by experiment, that different fluids at the sur- 
face of the earth boil at different temperatures, depending 
generally on the specific gravity of the fluid, and also, that 
the same fluid boils at various temperatures, depending on 
the degrees of atmospheric pressure. Thus, under the 
same pressure of the atmosphere, or on the level of the 
sea, water boils at 212 degrees ; ether at 100 degrees ; al- 
cohol 173 degrees; nitric acid, of the specific gravity of 
1,450, at 240 degrees, and water, saturated with sea salt, 
216 degrees. 

We may observe, that in these instances, the boiling of 
a fluid seems to follow a general law depending on its spe- 
cific gravity. This is strictly the case in respect to the 
boiling point of sulphuric acid, which always requires a 
temperature for its ebullition in a direct proportion to its 
specific gravity. 

Thus, according to Dr. Dalton, sulphuric acid, sp. gr. 
1,408, boiled at 240 degrees, while that of sp. gr. 1,670, 
boiled at 300 degrees; that of 1,780, at 435 degrees, and 
that of 1,850 at 620 degrees. 

The boiling point of a fluid is not, however, in all cases, 
to be estimated by its specific gravity, the fixed oils requiring 
much higher temperatures for their ebullition than other 
fluids of the same density. Thus, hnseed oil boils at 640 
degrees, though its specific gravity is less than that of water ; 
and mercury boils at about 660, though its specific gravity 
is about 14 times that of water. 

That water, or any other fluid, will boil with a less degree 
of heat, in proportion as the weight of the atmosphere is 
removed, may be readily proved by means of the air pump, 
or by ascending up a mountain, where the air is less dense 
than it is on the level of the sea. 



On what does the boiling temperature of fluids generally depend? Why 
is the boiling temperature of water, saturated with salt, higher than that ol 
pure water? What is said concerning the influence of specific gravity on 
the boiling temper?.ture of liquids ? Under what circumstances will wate- 
boil at a less temperature than 212 degrees? At what temperature doea 
water boil when the pressure of the atmosphere is removed ? 

2* 



18 STEAM. 

The most simple illustration of this subject, with the air 
Dump, may be made by means of a small vessel of ether : 
for if this be placed under the receiver, and the air exhausted, 
the fluid will boil, or turn to vapor, during ordinary temper- 
atures of the atmosphere. 

14. To make water hoil hy cooling it. — If a vessel of 
hot water, instead of the ether, be placed under the re- 
ceiver, and the air withdrawn from it, the water will 
continue to boil until its temperature is reduced down to 70 
degrees. 

In the absence of an air pump, the Fig. \. 

same principle may be stiikingly illus- 
trated as follows : Adapt a good cork to 
the glass flask, Fig. 1, so as to make it 
air tight : put a gill or two of water into 
it, and apply the heat of a lamp until it 
boils. After it has boiled for a short time, 
introduce the cork, and at the same time 
take the flask from the fire. It will con- 
tinue to boil for a few minutes after its 
removal. When the ebullition has ceased, 
it will boil again ^-iolently on plunging 
the flask into a jar of cold water, as 
seen in the figure. On taking it out of the water the 
ebullition will cease, but will instantly recommence if 
again plunged into the water : and this may be continued 
until the flask is nearly cold. 

In this experiment, the boiling is continued in consequence 
of the partial vacuum vrhich is occasioned by the condensa- 
tion of the steam with which the flask was at first fi-lled. 
If the flask be taken from the vessel of cold water, and 
plunged into one of hot water, the boihng will instantly 
cease, because the heat vrill convert a portion of the water in 
the flask, which had been condensed, into steam, and thus the 
partial vacuum, which had been formed, will be filled with 
vapor, the pressure of which will prevent further ebullition. 

This principle is beautifulh' illustrated hj the fact, that 
the higher we ascend from the surface of the earth, the 
lower will be the temperature at which water boils. The 
reason is ob\-ious ; the pressure of the atmosphere dimin- 

How may the pressure of the atmosphere be removed from a vessel of 
water, without the use of an air pump ? Why will the water in a vessel, 
Fig. 1, be made to boil by cold, and cease to boil by heat? V/hy does water 
DoU at a lower temperature on a high mo^intain, than on the level of the sea ? 




EVAPORATION. [q 

ishes in proportion to the ascent, and the boiling temperature 
sinks in proportion as the pressure is removed. 

15. Phenomena of boiling , on a mountain. — Upon tniB 
principle is constructed the thermometric barometer^ which 
indicates the elevation of any place above the level of the 
sea, by the temperature at which water boils at that eleva- 
tion. By experiment, it has been found that a difference in 
elevation, amounting to nearly 520 feet, makes a difference 
of one degree in the boiling point of water. A traveller, 
therefore, who ascends a high mountain, may ascertain 
nearh^ his elevation by the temperature at which he finds 
his tea-kettle to boil. Thus Saussure found that at a certain 
station on Mount Blanc, water boiled when heated to 187 
degrees. This being 25 degrees less than its boihng point 
at the level of the sea, allowing 520 feet for every degree, 
would give an elevation of 13,000 feet. This method can 
not, however, be very accurate, since the weight of the 
atmosphere at the same place varies at different times abo^U 
three inches of the barometric guage. [See Natural Phi- 
losophy, article Baro?neter.] 

EVAPORATION. 

16. During the process of ebuUition, there is a rapid for- 
mation of vapor, attended by more or less coramotion in the 
liquid. Evaporation also consists in the formation of vapor 
without heat, but the process is so slow as not to occasion 
any visible commotion in the fluid. Evaporation takes 
place, even during the coldest seasons, while ebullition re- 
quires various degrees of heat, or at least the removal of 
atmospheric pressure. 

To prove that evaporation takes place at ordinary tem- 
peratures, nothing more is necessary than to expose a quan- 
tity of water to the open air in a shallow vessel, when the 
fluid will be found gradually to diminish, and finally to 
disappear entirely. There is, however, a great difference 
in the rapidity with which different fluids evaporate, and in 
general it is found that those whose boihng points are lowest 
disappear most rapidly. Thus, ether and alcohol evaporate 
much more rapidly than water. 

What instrument is constructed on this principle ? How may a traveller 
who ascends a high mountain, ascertain nearly his elevation by the boiling 
of a tea-kettle ? What is evaporation ? How is it shown that evaporation 
takes place without the aid of heat? What relation does there seem to be 
between the boiling point of a fluid and its evaporation? 



20 EVAP0RAT10^\ 

The chief circumstances which influence evaporation are, 
extent of surface, and the state of the atmosphere in respect 
to temperature, moisture, and dryness. 

As evaporation takes place only from the surfaces of 
fluids, it is obvious that its rapidity must, under equal cir- 
cumstances, be in proportion to this extent of surface. Thus, 
a given quantity of water will evaporate four times as soon 
from a vessel two feet square, as it will from a vessel of one 
foot square. In respect to temperature, it hardly need to be 
remarked, that fluids evaporate more rapidly in warm than 
in cold situations, and that the process is hastened in pro- 
portion to the degree of heat employed. 

Fluids evaporate much more rapidly in a dry, than in a 
damp atmosphere. Even when the season is cold, if the air 
be dry, this process goes on rapidly, while it is compara- 
tively slow during the warmest season, if the air is already 
saturated with moisture. 

As evaporation consists in the formation of vapor, and 
the subsequent removal of successive portions of the evapo- 
rating fluid by the air which comes into contact with its 
surface, it is obvious that the process must be m^ore rapid in 
a current of air, than it is in a place where the air is still. 
And hence, we find by experience, that evaporation is more 
rapid in the open air than in the house, and that, under 
equal circumstances, is most speedily effected during a 
strong wind. 

17. We have already explained, that one of the peculiar 
circumstances attending the formation of steam, is the large 
quantity of caloric which it absorbs and carries away. Now 
it appears, by experiment, that the conversion of fluids into 
vapor always requires large quantities of caloric, which 
becomes latent in the vapor, however slowly the process is 
carried on, and hence, under ordinary circumstances, evapo- 
ration, by conveying off the heat, has the effect of generating 
cold. To make this fact sensible, by experiment, we have 
only to pour a little ether on the hand, when a strong sen- 
sation of cold will be felt during its evaporation. When 
our clothes are wet by a shower of rain, we feel cold for the 
same reason, but the sensation is less strong, because the 
evaporation of water is not so rapid as that of ether. 

What are the chief circumstances which influence evaporation ? Is evapo- 
ration most rapid in hot or cold weather? In '\\hat does evaporation consist ? 
Wliy is evaporation more rapid in the open air than in the house ? What is 
said concerning the latent heat of vapor ? How is cold produced by erapo 
ration? 



EVAPORATION. 21 

It has been explained that water boils at a lower tem- 
perature, in proportion as the pressure of the atmosphere is 
removed. For the same reason, evaporation under equal 
circumstances, is most rapid when the weight of the atmos- 
phere is removed, as under the exhausted receiver of the 
air pump. 

The cooling- effects produced hy the evaporation of water 
in the open air are not strikingly apparent, because the pro- 
cess is comparatively slow, and, therefore, the quantity of 
caloric carried away from a body in any given time, is but 
little more than it receives from surrounding objects. But 
when water is placed in a vacuum, its evaporation is very 
rapid, and did not the vapor from it fill the vacuum, and 
thus prevent farther evaporation, the heat would be carried 
away so rapidly as soon to turn the water to ice. 

Cryopho- Fig. 2. 

rus. — This 
curious ef- 
fect is pro- 
duced by 
means of an 

mstrument invented by Dr. Wollaston, and called the Cry- 
ophorus, or Frost-Bearer, Fig. 2. It consists of two glass 
balls, as free from air as possible, and joined together by a 
glass tube. One of the balls contains a portion of distilled 
water, while the other parts of the instrument, which appear 
empty, are full of aqueous vapor, which prevents the farther 
evaporation of the water, by the pressure the vapor exerts 
on it. But when the empty ball is plunged into a freezing 
mixture, all the vapor w^ithin it is condensed ; and then the 
evaporation becomes so rapid from the water in the other 
ball, as to freeze it in a few minutes. To make this experi- 
ment succeed, the tube should be a yard long, the balls 
holding about a quart each. The same effect on water will 
be produced by the evaporation of ether under the exhausted 
receiver of an air pump. 

19. To freeze water hy evaporation. — This experiment 
may be conveniently made by placing a little water in a 
glass cup, and covering it with ether, after which suspend 



Does the pressure of the atmosphere influence this process ? Why does not 
the evaporation of water from the surface of the earth produce intense cold ? 
How may the evaporation of water be made so rapid as to turn itself into 
ice ? What is the instrument, Fig. 2, called ? 



EVAPORATIOIs\ 




the cup within the receiver of the air pump, Fig. 3. 
as shown at Fig. 3. On exhausting the 
receiver, the ether will boil, in consequence 
of its rapid evaporation, and in a few min- 
utes the water will be frozen. 

Evaporation takes place constantly, from 
the surfaces of our bodies, and it is owing 
to this circumstance that men are enabled 
to undergo exercise during the heat of sum- 
mer. 

In general, the more violent the exercise, 
the greater is the quantity of perspiration 
arising from the surface, and consequently 
the greater the quantity of heat carried 
away. In this manner nature regulates 
the heat of the system, and during health sustains the equi- 
librium of animal temperature. Whenever this exhalation 
from the skin is suppressed, which only results from dis- 
ease, the temperature of the system rises, and fever suc- 
ceeds. In some cases of this kind, the heat of the human 
body exceeds that of the standard of health by seven or 
eight degrees. 

The natural temperature of the human body in health, is 
about 98 degrees, and whenever the heat of summer is equal 
to that of the body, it becomes exceedingly oppressive. The 
least exertion then brings on copious perspiration, which, in- 
deed, prevents the immediate consequence of a higher ani- 
mal temperature, but which is generally succeeded by 
languor and debility. 

20. Animals resist heat and cold. — It is a wonderful fact, 
that the living animal has the power of resisting both heat 
and cold, and of maintaining its own temperature, whatever 
may be the temperature of the air or water in which it is 
immersed. Sir Joseph Banks, and Sir Charles Blagden, 
found by experiment that they could endure for a short time 
the heat of a room, the temperature of which was 264 de- 
grees, that is, 52 degrees hotter than boiling water. These 
gentlemen found that their hands could not bear the heat of 
their watch-chains, or metallic buttons, but that their chests 



How may water be frozen by the evaporation of ether ? From what pro- 
vision of nature are we enabled to use violent exercise in warm weather ? 
How does perspiration relieve us from the effects of excessive heat ? What 
is the effect of suppressed perspiration on the temperature of our system? 
What is said ot the power of animals to resist heat as well as cold ^ 



CONDUCTORS OF CALORIC. 23 

felt cold, and that the temperature of their bodies was not 
elevated above 98 degrees. In this room, eggs placed in a 
tin frame, were roasted in twenty minutes, and beef-steak 
was well cooked in about the same time. 

CONDUCTORS OF CALORIC. 

21. Some bodies have the power of conducting caloric 
much more rapidly than others. Thus one can hardly hold 
a brass pin for a moment, in the flame of a lamp, without 
burning his fingers, while a piece of glass of the same size, 
may have one of its ends melted, without warming the 
other. 

22. Bodies which are most dense are generally the best 
conductors. Thus the metals conduct better than stones ; 
stones better than earth ; earth better than wood ; and wood 
better than charcoal, cloth, or paper. But in particular 
cases there is no relation between the density of the body. 
and its power to conduct caloric. Thus platina is the most 
dense of the metals, and still it is one of the worst conduc- 
tors among them ; and glass is a worse conductor than 
many substances of less than half its density. 

23. The following table presents the relative conducting 
powers of the most important metals, and a few other sub- 
stances. The experiments by which these results were ob- 
tained, appear to have been conducted with much care. 
The substances were made into prisms of the same size and 
length, and while at one end the same degree of heat was 
applied to all, the temperature of each was seen by little 
thermometers, all graduated alike, the bulbs of which were 
set into the substance of each prism. By such means the 
foUowino- results were obtained : 



Gold - - 1,000 


Tin - - 304 


Silver 973 


Lead - - 179 


Copper - - 898 


Marble - - - 24 


Platinum- - 381 


Porcelain - 12 


Iron - - - 374 


Fine Clay - 11 


Zinc - - - 363 




Solid substances, such as 


the metals, conduct caloric in 


all directions, whether upwa 


irds, downwards, or sideways, 


with nearly equal facility. 





What striking illustration is given of the power of men to resist heat ? What 
bodies are generally the best conductors of heat ? Are the most dense bodies 
always the best conductors of heat ? How are the conducting powers of 
different bodies ascertained '' 



24 CONDUCTORS OF CALORIC. 

24. Of all solids, those which are most porous, conduct 
heat with the least facility. It is on this account that flan- 
nel is warmer in the winter, than silk or linen. It does not 
so readily conduct away the animal heat. It is owing to 
the air, which loose spongy substances involve, that they 
resist the passage of heat better than those of a closer tex- 
ture. Thus eider down, and fur, make the warmest cloth- 
ing, because they contain the most air among their parts, 
and for the same reason cotton batting is much warmer than 
the same weight of cotton cloth. 

25. The imperfect conducting power of snow, also arises 
from this cause. When newly fallen, a great proportion of 
its bulk consists of the air which it contains, as may be 
readily proved by the comparatively small quantity of water 
it makes when melted. Such a provision was designed for 
the benefit of man, in preventing the destmction of various 
products of the earth during the cold of winter. Farmers, 
in cold climates, always lament the nakedness of the earth 
during the winter, because many of their crops are in con- 
sequence injured by its severity. So great is the protecting 
effect of snow, that in Siberia, it is said, when the tempera- 
ture of the air has been 70 degrees below the freezing point, 
that of the earth, under the snow, has seldom been colder 
than 32 degrees. 

26. Our ordinary sensations every day convince us of the 
different powers of various substances to conduct heat. In 
the winter, the different articles in a cold room convey very 
different sensations to the hand. A pair of tongs will con 
duct away so much heat from the hand as to give a sensa 
tion of pain, while a piece of fur, or flannel, scarcely feels 
cold, and yet both are of the same temperature, when tested 
by the thermometer. 

27. Conducting power of liquids. — Liquids communicate 
heat with considerable rapidity, though they conduct it so 
imperfectly that Count Rumford, after many experiments, 
concluded that they were absolutely non-conductors. 

28. Liquids convey heat chiefly by a change of place 

What kind of solids are the worst conductors of caloric ? Why do loose 
spongy bodies conduct heat more slowly than others ? Why is cotton batting 
warmer than the same weight of cotton cloth ? In what manner does snow 
protect the earth from the cold of winter ? What is said to have been the 
difference between the temperature of the air, and the earth covered with 
snow, in Siberia ? Why does a pair of tongs feel cold, when a piece of flan- 
nel or fur, at the same temperature, gives no sensation ? How do liquids 
convey caloric ? 



OMM (;roK.> (IF CALOKIU *^ 

Mixuij^ I eir panicles. When a vessel ot water is placeii 
over the fire, that portion of the fluid nearest the neat having 
imbibed a portion of caloric, becomes hghter than before, and 
rises upward, communicating a part of its heat to the por- 
tions above. At the same time, that which is above sinks 
to the bottom of the vessel, and having obtan ed its portion 
of caloric, again rises, giving out a share to tht surrounding 
fluid, like the former. In this manner does the water in the 
^iifFerent parts of the vessel exchange places until the whole 
gains the temperature of 212 degrees. 

29. But though fluids convey heat chiefly by exchanging 
the places of their particles, yet they are not wholly without 
the power of conducting it in any direction. 

Count Rumford, w^e have already stated, decided from 
his experiments that liquids were perfect non-conductors of 
heat ; but Dr. Murray, and since him, other experimenters, 
have estabhshed the contrary doctrine. Dr. Murray's appa- 
ratus consisted of a vessel of ice, at the bottom of which 
was placed a dehcate thermometer. The vessel was then 
partly filled with oil, at the temperature of 32 degrees, so as 
to cover the bulb of the thermometer ; and nearly touching 
the oil, was suspended an iron cup, into which was poured 
a quantity of boihng water. In seven and a half minutes 
the heat from the water had raised the thermometer from 
32 degrees to 37| degrees, when it became stationary, and 
then gradually began to fall. 

30. Dr. Hope placed water in a vessel of elb ^n inches 
in diameter, and so contrived his apparatus, that a -tream 
of cold water should circulate around this vessel, to present 
its conducting power from affecting the result. He then 
a pplied heat to the upper surface of the water in the vessel, 
and found by the indications of a thermometer placed in it, 
that the fluid conducted the caloric downwards. 

By such nice experiments only has it been ascertained, 
that fluids conduct heat downwards ; while under all ordi- 
nary circumstances, they may be considered perfect non- 
conductors. 

EXPANSIVE POWER OF HEAT. 

31. One of the most remarkable properties of heat arises 
from the mutual repulsion of its particles, so that when it 



Are fluids wholly without the power of conducting caloric ? By what 
method did Dr. Murray determine that fluids were conductors of caloric ? En 
what manner did Dr. Hope ascertain *.he same fact^ 
2 



/. ■, 



26 



EXPANSION BY HEAT. 



enters into other substances, it overcomes the cohesive at- 
traction of their parts, making them less dense than before, 
and thus enlarging their dimensions. In general terms, 
therefore, heat expands all bodies. The ratio of this expan- 
sion, however, differs greatly in different substances. Thus, 
with the same increments of heat, fluids expand more than 
solids, and aeriform bodies more than fluids. There is also 
a considerable difference in the expansibility of different 



aeriform fluids, as air 



1 Q 



a 



Fis. 4. 



solids and different liquids ; but the 

and the gases, all expand equally, with the same increase 

of temperature. 

32. The expansion of a solid is readily proved, by adapt- 
ing a piece of metal, when cold, to an orifice, or notch, and 
then heating it, when it will be found too large for its for- 
mer place. 

The cylindrical piece of brass, at- 
tached to the handle a, fig. 4, is exactly h 
fitted to the notch in the plate Z>, and 
also to the aperture through the plate, 
so that it will enter the notch, and pass 
through the aperture, when cold ; but 
when heated, even below redness, it 
will neither enter the notch, nor pass 
through the aperture. This proves 
that heat enlarges, or expands the di- 
mensions of solids in every direction. 

33. The relative degrees of expan- 
sion which different solids undergo, at 
low degrees of heat, are shown by an 
instrument called the pyrometer^ one 
form of which is seen at Fig. 5. 

A rod of 
any metal, a, 
is laid on 
the rests, 
and one 
end made 
to touch 
the im- 
movable 
screw, 5, 
while the 
Other end 



8 




How does heat operate to enlarge the dimensions of bodi 



EXPANSION BY HEAT. 27 

touches the index c. The rod is then heated by the spirit 
lamps d, and its comparative expansion is shown by the 
multiplied motion of the index e along the graduated scale. 

In comparing diiferent substances by means of this instru- 
ment, it will be necessary that all the rods should be of the 
same size and length, and that the heat of the lamps should 
be applied the same length of time. 

From experiments made with this instrument, it appears, 
that in most instances, there is a relation between the ex- 
pansion of the metals, and their fusibility, and in general, 
that those which are most easily fusible, expand most with 
equal increments of heat. Thus lead, tin, and zinc, expand 
much more by the same degrees of heat, than copper, silver, 
and iron, and the former are much, more easily fusible than 
the latter. 

34. The expansion of the metals by heat, is often turned 
to advantage by certain mechanics and artizans in their bu- 
siness. In constructing large cisterns for brewers, or other 
manufacturers, the hoops are made too small for the circum- 
ference of the vessel. They are then heated, and in this 
state driven on the vessel, and as they contract in cooling, 
the vessel is thus bound together more firmly than could be 
done by any other means. Carriage-makers, by heating 
the iron band, or tire, which surrounds the wheels of car- 
riages, and putting it in its place while hot, bind these parts 
together with the greatest possible firmness. 

35. The great force with which metals contract on cool- 
ing, was strikingly illustrated some years since in Paris. 
The two sides of a large building in that city, having been 
pressed out by the weight of its contents and the roof, M. 
Molard proposed to remedy the evil, by making several holes 
in the two v/alls, opposite to each other, through which 
strong iron bars should be introduced, so as to cross the in- 
side of the building, from one wall to the other. On the 
projecting ends of the bars, on the outside of the building, 
were screwed strong plates of iron. The bars were then 
heated, by which their ends v/ere made to project further 
beyond the v/alls, thus permitting the plates to be advanced, 
until they again touched the walls, which might be an inch. 

What bodies expand least, and what most, by heat ? What is said of the 
equal expansion of air and the gases by heat ? How is the expansion of a 
piece of metal shown by Fig. 4 ? How are relative degrees of expansion 
which solids undergo ascertained? Explain Fig. 5. What relation is there 
between the expansion of metals and their fusibilities ? 



28 KXPANSION BY HEAT. 

or jnore. The bars, then, on cooling, contracted, and drew 
tho walls as much nearer each other as the bars expanded 
m heatmg. There were two sets of these bars, so that, 
while one set was contracting and drawmg the wall to its 
place, the other set w^as heating, and preparing to retain 
what was thus gained. In this manner, a force was exert- 
ed, which the power of man could scarcely have apphed by 
any other means, and by which the walls of an immense 
building were made to resume their perpendicular position. 

36. The expansion of a liquid by heat, may be strikingly 
shown by means of a glass ball, with a long small tube at- 
tached to it. When the ball, and a part of the neck, are 
filled with a liquid, and heat applied to the ball, the hquid 
expands, and continues to rise up the tube with considerable 
rapidity, until the liquid boils, when it will be thrown out 
with great force by the steam. 

37. The different expansibilities of different fluids by the 
same increase of heat may be shown by two such vessels as 
that just described. 

On the tube of each, fix a mark at the same Fig. 6. 
height, and fill one up to the mark with alcohol, 
and the other with water. Then plunge the rj p, 
bulbs of both into the same vessel of boihng hot 
water, thus making the heat applied to each 
exactly equal. Both the fluids will expand, 
and rise up the tubes, but the alcohol will be 
found to rise about twice as high as the water. 

It has already been remarked, that the ratio 
of expansion in all aeriform fluids, is equal, with 
equal increments of heat. 

If therefore, the ratio of expansion for one gas, 
as for instance, oxygen, be known, then the 
ratio for all the other gases, as well as that for 
the common air, which we breathe, will be indicated. 

38. From the experiments of several philosophers, it is 
proved, that this rate of expansion is equal to the ^loih part 
of the volume which the gas occupied, for every degree of 
Fahrenheit's scale, at 32 degrees and upwards. This cal- 
culation is made from the experiments of Gay Lussac, who 

Ir. what mechanical arts is the expansion of the metals, by heat, turned to 
advantage 1 In what manner were the w^alls of a building in Paris drawn 
towards each other by means of heat? In what manner is the expansion of 
a fluid most strikingly shown ? How are the different expansibilities of 
different fluids shown ? Explain Fig. 6. 



RADIATION OF HEAT. 



29 



found that 100 parts, or volumes of air, at 32 degrees, ex- 
panded to 137.5 parts, when heated to 212 degrees. The 
increase of bulk for 180 degrees, that is, from the freezing 
to the boiUng point, is therefore 37^, which, by calculation, 
will be found nearly jlrMi part for each degree. 

39. The expansion of air by heat may readily be shown 
by blowing up a bladder, and securing the mouth by a 
string, so that none can escape, and then holding it towards 
the fire. As the air becomes rarefied by the heat, the blad- 
der will become more and more tense, until it bursts with 
an explosive report. 

40. A more elegant experiment is, to 
take a glass tube, terminated by a bulb, 
and put in so much water as to about half 
fill the tube, and then, having immersed 
it in a vessel of water, as represented in 
Fig. 7, apply the heat of a lamp to the 
bulb. As the heat rarefies the air in the 
bulb, the water will be forced down the 
tube, but will slowly rise again to its 
former place, by the pressure of the at- 
mosphere on the fluid, when the heat is 
removed, and the air in the ball allowed 
to contract. 



Fig. 7. 




RADIATION OF HEAT. 

41. When we approach a heated body we become sensi- 
ble that it emits caloric without touching it, and if a ther- 
mometer be carried near, this will indicate an increase of 
temperature. The caloric thus flowing from a heated body, 
is called radiant caloric, because it radiates, or is thrown oflf 
in all directions, like the rays of light from a radiant point. 
If the hand be held under the heated body, a sensation of 
warmth will still be perceived, which proves that this effect 
is produced without the intervention of a stream of heated 
air, which is felt only above the hot body, and never below 
it. Neither is this eflfect produced by the gradual conduc- 
tion of the caloric by the air, for the heat from a hot ball 
may be felt in the open air, at a distance from it, and in the 

How much more expansible is alcohol than water ? What is the "atio of 
expansion in aeriform bodies ? What is the difference in the bulk of 100 parts 
of air at the freezing and boiling points of water? What simple experi- 
ments show the expansion of air by heat ? Explain Fig. 7. What is meant 
by radiant heat? How is it proved that radiant heat is not conducted by 
the air? 

3* 



30 



RADIATION OF HEAT. 



direction contrary to that of the wind. It is found also, that 
caloric radiates equally well through all the gases, and 
better through a vacuum than any medium ; and hence we 
may infer that no medium at all is necessary for the passage 
of radiant caloric. 

42. When radiant caloric falls upon a solid or liquid, its 
rays are either reflected from it, and thus receive a new 
direction, or they lose their radiant form entirely by absorp- 
tion into the body. Thus, a substance highly polished will 
throw the heat back towards the radiating body, and remain 
cold itself; while another substance, with a rough surface, 
will become warm at the same distance, because it absorbs, 
but does not reflect the heat. Radiant heat and light follow 
exactly the same laws in their passage to and from polished 
surfaces, the angles of incidence and reflection being equal. 

43. Thus, the ray «, c, Fig. 8, is the ray 
of incidence, and c, d, is the ray of reflection. 
The angles which a c make w4th the per- 
pendicular line e c, and the plane of the 
mirror, are exactly equal to those made by 
c, d, with the same perpendicular and plane 
Burface. {See Optics in Nat. Philosophy.) 
Hence, with a concave mirror, the rays of 
heat, like those of Hght, may be concentra- 
ted, or collected to a focus, and by means 
of two such mirrors, very interesting experi- 
ments may be made, illustrating the laws of radiant heat, 
in several respects. 

44. Provide a pair of concave metallic mirrors, about ten 
or twelve inches in diameter, and two in concavity. They 
may be made of common tinned iron, or of brass, which is 
better, but much more expensive. 

Fisr. 9. 





O <^ 




^ C^ 



How is it shown that no medium at all is necessary to oonvev radiant caloric ? 



RADIATION OF HEAT. 3 1 

These mirrors may be supported by stands made of 
wood, on which they sHde up and down, and are fixed by 
thumb-screws, as represented in Fig-. 9. Place the min'ors 
at the same height on a bench or table, exactly facing each 
other, and from ten to twenty feet apart, as they are less or 
more perfect, and place a s reen of paper, or other sub- 
stance, between them. Tb ;n, in the focus of one mirror, 
place a cannon ball, heated a little below redness, and in 
the other focus place a thermometer. When every thing 
is thus prepared, remove the screen, and the thermometer 
will instantly begin to rise, and will finally indicate a de- 
gree of temperature depending on the size and perfection 
of the mirrors, their distance apart, and the heat of the ball. 
The focus of a twelve-inch mirror, of the ordinary shape, 
is about four and a half inches distant from the centre of 
concavity. 

By placing the mirrors near each other, and using a red 
hot ball, a much more striking experiment may be made, 
for on removing the screen, powder will flash in the focus, 
as if by magic, since the eye cannot detect the cause on 
which its inflammation depends. 

45. The dotted lines in the drawing, Fig. 9, show the 
course of the rays of heat from the hot ball to the ther- 
mometer. The ball being placed in the focus of the mirror, 
the caloric radiates to all parts of its surface, and being 
reflected under the same angles at which it falls, the rays 
are thrown into parallel lines, and thus become incident 
rays to the second mirror. By the same law of incidence 
and reflection, the second mirror conveys the rays to a focus 
at the same distance before it that the hot ball is placed 
before the first mirror, because their focal distances are just 
equal. The heat of the ball is therefore concentrated on 
the bulb of the thermometer, which is placed in the focus 
of this mirror. If a burning lamp be placed in the focus 
of the first mirror, and a piece of paper, or the hand, in the 
focus of the second, there will be seen a bright, luminous 
spot on the paper, or hand, showing that light follows the 
same laws of reflection that heat does. 

46. There is, however, a remarkable difference between 



Does heat radiate through solid bodies ? Explain Fig. 8, and show which 
IS the ray of incidence, and which that of reflection ? Explain Fig. 9 ; show 
the direction of the rays of heat from the heated ball to the mirrors, and from 
the mirror to the thermometer. How is it shown by the mirror that heat and 
light follow the same laws of reflection ? 



^2 



RADIATION OF HEAT. 



the substances of which mirrors are commonly made, with 
respect to their powers of reflecting heat and hght. A 
concave glass mirror, covered in the usual manner with 
amalgam, when placed before a red hot cannon ball, will 
reflect the light, but not the heat, the mirror itself absorbing 
the radiant caloric, and soo growing warm. But a well 
polished metaUic mirror refle ts both the heat and light, 
and although held so near an ignited bodj^, as, were it com- 
bustible, to be inflamed, it still remains cold. For the same 
reason, andirons, which are kept highly polished, will re- 
main colli though near a winter's fire. Any one who has 
undertaken to boil water in a silver cup, before the fire, will 
be convinced of the power of a bright metallic surface to 
resist the penetration of caloric. 

The nature, or colors of the surfaces of bodies, have also 
an important influence over their power of radiating caloric. 

47. When other circumstances are equal, the rate at 
which bodies cool appears to be in an inverse ratio to the 
polish, or brightness of their surfaces. Thus, the surfaces 
of bodies are found to radiate heat more rapidly when they 
are rough than when smooth, and mos* rapidly when their 
surfaces are both rough and dark coloied. 

48. Mr. Leshe covered one side of a cubical tin vessel 
with lampblack; another side with writing paper; a third 
with glass, and left the fourth uncovered. 

The vessel was then filled with hot water, and placed 
before a concave mirror, in the focus of which was placed 
an air thermometer, as re- 
presented by Fig. 1 0. On 
turning the black side to- 
wards the reflector, the 
fluid in the thermometer 
indicated a rise of tempera- 
ture equal to 100 degrees; 
the papered side being 
turned towards the reflec- 
tor, the thermometer sunk 
to 93 degrees; the glass 
side indicated 90 degrees, 
and the metallic side only 

WViat is the difference between a mirror of glass, and one of metal, in theii 
powers to reflect heat and light ? Why do polished andirons remain cold, 
■when near the fire ? Why is it difficult to boil water in a bright metallic 
Tessel ? What effect does the nature, or «olor of ;> surface, have on its radia- 
ting power '' 



Fis. 10 




TRANSMISSION OF HEAT 33 

12 degrees. The radiating power of these surfaces iere- 
fore, are respectively to each other, as the numbers 1*^0,98, 
90, and 12. 

Various practical uses may be made of this principle in 
the common concerns of Hfe. 

49. A close stove, intended to warm a room by radiating 
its heat to the objects surrounding it, should be dark col- 
ored, with a rough surface; while one intended to warm 
with hot air passing through it, should have a bright, me- 
tallic surface. A dark, rough stove pipe, passing through 
a room, might render it comfortably warm; while a po- 
hshed tin pipe, of the same length and dimensions, would 
hardly change its temperature perceptibly. For the same 
reason, a highly polished metalUc coffee-pot will keep its 
contents hot, while the contents of one made of dark earthen 
ware would become nearly cold. 

TRANSMISSION OF HEAT. 

50. Raj^s of heat, in passing through air, are no more 
obstructed than those of light ; but in passing other trans- 
parent media, heat is obstructed in various degrees, depend 
ing on some unknown property of the substance. It is well 
known that the rays of the sun, consisting of light and 
heat, may be so concentrated, by means of a paraboHc mir- 
ror, as to fuse a metal, or inflame a combustible; and if a 
transparent body, as a plate of glass, be held between the 
sun and the mirror, or between it and the combustible, the 
effect will be but little, if at all diminished. 

51. Now if the same experiment be made with a common 
fire, or a number of lamps, though the heat and light are 
concentrated as before, yet if the glass plate be interposed, 
the heating effect, instead of remaining undiminished, as in 
the experiment with the sun, is reduced almost to nothing, 
while the spot of light remains as bright as before. Thus^ 
the rays of heat, coming from the sun, pass through glass 
without difficulty, while the same substance almost entirely 
intercepts those made by art. 

52. It is not, how^ever, to be understood that glass is ab- 
solutely impermeable to artificial radiant heat, for it has 

Describe Fig. 10, and explain how the different surfaces affect the thermome- 
ter ? What practical uses maj' be made on the principles established by Mr. 
Leslie's experiment ? Why does a bright coffee-pot keep its contents warm 
I( 'er than one that is tarnished ? What is said of the passage of the sun's 
hct through glass? What effect does a plate of glass have on the pa.ssago 
of culinary heat ? Does glass entirely interc n the rays of artificial heat f 
2* 



34 RAlNSMISSfON UF HEAT. 

beer, found that the intense ignition of charcoal by voltaic 
action, produces an effect on the air thermometer when 
passed through a glass lens, and also that thin plates of the 
same substance will transmit indications of the heal of a 
powerful gas-burner. 

53. Transmission of heat hy different substances.— On this 
subject, M. Melloni, a French chemist, has made a series 
of curious and important experiments. These were made 
by means of the thermo-multiplier^ an instrument much more 
sensible to small degrees of heat than the air thermometer. 
This instrument is constructed on the principle of thermo- 
electricity^ of which the following is a description ; first in- 
forming the student, that when two bars of different metals 
are connected together at each end, if one of the joints is 
heated more than the other, a current of electricity is imme- 
diately produced. 

54. Thermo-electrical piles. — Now if a magnetic needle 
be exposed to the influence of the above described electrical 
current, it will be moved, or deflected out of its true position, 
even though only a single pair of bars be employed ; and 
hy using a series of such bars, and heating their alternate 
ends, the intensity of the electrical influence may be increased 
to any desirable extent. Such an instrument is called a 
thermo-electric pile. That used by M. Melloni in his ex- 
periments consisted of fifty -five bars of antimony, and as 
many of bismuth, laid side by side, with their alternate ends 
soldered together. Fig. 1 1 repre- 
sents this thermometer; a, the pi^ \\ 
metalHc bars ; 5, a lamp heating 
one end of the pile, by which the 
electricity is developed, and the 
magnetic needle, c, is moved. The 
lamp being removed, and the end 
of the pile blackened, in order to 
promote the absorption of the rays 
of heat, the substances, whose 
powers of transmission were to 
be examined, having been cut into thin plates, were placed 
before the end of the pile. A screen, having an aperture 
equal to the face of the pile, was placed between the source 



What is meant by thermo-electricity ? What effect does the thermo- 
electrical current have on the magnetic needle ? How is the thermo-electric 
pile constructed? In what manner is the pile employed? 




SPECIFIC CALORIC. 35 

of heat, and the plate to be tried, while a second screen m 
tercepted the rays of heat until the instant of trial. 

55. By such"^ means, M. Melloni obtained very curious, 
and often very unexpected results ; and, among others, that 
bodies which transmit light most freely, often almost entirely 
intercept the rays of heat, while other transparent bodies 
are as permeable to heat as to light. 

56. Bodies which allow the ready passage of heat, are 
called transcalent^ or diathermanous, while those which in- 
tercept its rays are called intranscalent, or adiathermanous. 
Among all substances, rock salt is most highly transcalent, 
admitting the rays of heat to pass through it with very 
little interruption ; while alum, and glass, though fully as 
pervious to hght as the salt, almost entirely intercept the 
calorific rays. On the contrary, some substances, though 
nearly opaque, with respect to hght, admit the passage of 
heat with considerable facility, such as brown rock crystal, 
which was found nearly as transcalent as the most colorless 
specimens of the same material. 

57. Bodies absolutely opaque, as wood, metals, and black 
marble, intercepted the rays of heat completely, although it 
was found that the faculty of transmission was possessed to 
a certain degree by nearly opaque substances, as thick 
plates of brown quartz, black mica, and black glass. 

SPECIFIC CALORIC. 

58. Equal weights of the same substance, at the same 
temperature, contain equal quantities of caloric ; but equal 
weights of different substances, at the same temperature, 
contain unequal quantities of caloric. The quantity pe- 
culiar to each body, or substance, is called specific caloric. 
When one body of the same weight is found to contain 
more caloric than another, that containing the most is said 
to possess the greatest capacity for caloric. 

59. When equal quantities of the same fluid, at different 
temperatures, are mingled together, the resulting tempera- 
ture is a medium between these temperatures. Thus, if a 

What singular results were obtained by means of this pile ? What are 
transcalent bodies ? What are intranscalent bodies ? What difference is 
there between the transcalence of rock salt and alum 1 What is said of glass 
as a transcalent body? What substances are mentioned, which transmit 
heat without light ? Do substances entirely opaque transmit heat ? What is 
meant by specific caloric ? What is meant by capacity for caloric ? Suppose 
equal quantities of the same fluid, at different temperatures, are mixed, what 
will be the resulting temperature ? 



6 SPECIFIC CALORIC. 

quart of water at 100 degi^ees, be mixed with another quarl 
of water at 40 degrees, the temperature of the mixture will 
be 70 degrees. The same result will occur when any other 
liquid is mixed in equal proportions, but at different tern 
peratures, as oil, alcohol, or mercurj. But when equal 
quantities of different fli Js are mingled together at differeni 
temperature'^', the resulting tei perature is not a medium, 
but is either above or below it. 

60. We should expect, withoit experiment, that quick- 
silver would possess a greater capacity for caloric than the 
same bulk of water, and, therefore, that when equal quan- 
tities of these two fluids, at different temperatures, are mixed, 
the resulting temperature would be above the arithmetical 
mean. But in this we are disappointed; for if we mix a 
quart of water at 40 degrees, with a quart of quicksilver at 
100 degrees, the temperature of the mixture will not be 70 
degrees, as in the experiment with the water alone, but only 
60 degrees. This proves that a quart of quicksilver, al- 
though it weighs about fourteen times as much as a quart 
of water, still contains less caloric, and, therefore, that water 
has a greater capacity for caloric than quicksilver; for, in 
the first experiment, a quart of water at 100 degrees, raised 
the temperature of another quart at 40 degrees, to 70 de- 
grees ; but here, a quart of quicksilver at 100 degrees, raises 
the heat of the same bulk of water to only 60 degrees. The 
quicksilver, then, loses 40 degrees, which nevertheless raises 
the temperature of the water only 20 degrees. 

61. The relative capacities of water and quicksilver for 
heat, may be shown by mixing equal weights of the two 
fluids at different temperatures, and then ascertaining how 
much the resulting temperature differs from the arithmetical 
mean. 

Mix a pound of water at 100 degrees with the same 
weight of mercury at 40 degrees, and the heat of the mix- 
ture will be 98 degrees; that is, 28 degrees above the 
arithmetical mean, because when equal weights of water 
were mixed at these temperatures, the resulting temperature 
was only 70 degrees ; but here it is 98. The water, then, 
has lost only 2 degrees, while the same weight of mercury 



When fluids of different kinds are mi.xed under the same circumstances, 
will the resulting temperature be a medium ? Which fluid has the greatest 
caDHciiy for caloric, water or quicksilver ? How is this shown ? If a pound 
of mercury at 40 degrees be mixed with a pound of water at 100 degees, 
what will be the resulting temperature'' 



SPECIFIC CALORIC. 37 

has gained 58 degrees, for the temperature of the mercurv 
before the mixture was only 40 degrees, while that of the 
water was 100 degrees. The capacity of water for heal, 
is therefore to the capacity of mercury for the same, in the 
pioportion of 58 to 2, or as 29 to 1. 

62. It appears from a great variety of experiments made 
by different philosophers on this curious subject, that what- 
ever may be the cause of the different capacities of bodies 
for heat, the effect is greatly influenced by the state of 
density in which such bodies exist, and that. in general their 
capacities increase, in a ratio to the decrease of their specific 
gravities. In the above experiment, the capacity of water 
is to mercury as 29 to 1, while their specific gravities are as 
I to 14. 

63. Various methods have been employed by philosopher? 
to ascertain the capacities cf the several gases for heat. 

64. To determine and compare the relative capacities of 
these bodies in this respect. Gay Lussac contrived an ap- 
paratus, by means of which, a hot current of one gas met a 
cold current of another gas, in the centre of a small reser- 
voir, containing a thermometer. A thermometer was also 
placed in the current of each gas before they met. Thus 
by knowing their temperatures before their mixture, and 
afterwards, it was easy to infer their respective capacities 
for caloric. 

65. Bernard, in order to determine the specific caloric of 
elastic fluids, caused them to pass through a pipe inclosed 
in a larger pipe, the latter being constantly filled with 
steam. In this manner he was enabled to know precisely 
the temperature of the gas under experiment, and also to 
raise the temperature of each to the same degree. Having 
thus determined its temperature, the gas was then made to 
pass into a spiral tube immersed in cold water, and the 
specific caloric of each gas was inferred by the quantity of 
heat it imparted to the water. By these and similar ex- 
periments, it has been ascertained that the aeriform fluids 
differ greatly in the quantities of their specific caloric, — thus, 
the capacity of hydrogen for caloric is more than 12 times 
greater than the capacity of an equal bulk of atmospheric 

What are the proportionate capacities of mercury and water for heat? In 
general, do the capacities of bodies for heat increase, or decrease, with their 
densities ? By what method did Gay Lussac determine the capacities of the 
gases for caloric ? By what method did Bernard determine the capacities of 
the gases for caloric? What gas has the greatest capacity for heat? 

4 



38 VAPORIZATION. 

aiij tiiough the air weighs about 13 times as mucii as the 
hydrog-en. It is also ascertained that out of nine gases on 
which experiments were made, none except hydrogen has 
a capacity for heat equal to that of water, but that they all 
have greater capacities than any of the metals. Hydrogen, 
the lightest of all bodies, has the greatest capacity for heat, 
while the metals, the most ponderous of all bodies, have 
the least, 

66. The same substance by having its bulk enlarged, 
and consequently its density decreased, acquires an in- 
creased capacity for caloric. Thus water, when thrown 
on the bulb of a thermometer, sinks the mercury, because, 
in assuming the form of vapour, its capacity for caloric is 
increased, and it consequently absorbs and carries away 
the heat from the mercurj^ Some philosophers have ac- 
counted in part, for the intense cold in the upper regions of 
the atmosphere, on the supposition of the increased capacity 
of the air for heat as the pressure of the incumbent atmos- 
phere is removed. On the contrary, we know, that by 
increasing the density of air, its capacity for caloric is 
diminished, and that under certain circumstances sufficient 
heat may be set free in this manner to produce ignition, 

67. This effect may be produced by the little 
instrument represented by Fig. 12. It consists Fig. 12. 
of a metallic tube, ten or twelve inches long, the 
bore of which is less than half an inch in diame- 
ter. To this is fitted a rod and piston, moving air 
tight, the lower end of the piston being excavated 
to receive a little tinder. When the piston is sud- 
denly forced down, nearly to the bottom of the 
tube, the condensation of the air it contains, evolves 
so much heat, as to set fire to the tinder in the end 
of the piston, and in this way a fire may conven- 
iently be kindled, 

VAPORIZATION, 

68. By vaporization or evaporation is meant the conversion 
of a liquid, or solid into an aeriform body. This, with re- 
spect to most solids is performed by heat more or less intense, 



In general, what class of bodies have the greatest, and what the least 
capacity for heat ? If a body has its bulk enlarged, is its capacity for heat in- 
creased or diminished thereby ? How has the intense cold of the upper re- 
gions been accounted for on this principle ? How is it proved that the air 
has less capacity for heat when condensed than otherwise ? 



VAPORIZATION. 39 

ftccorcling to the nature of the substance, and it is even sup- 
posed that with sufficient degrees of heat, all substances 
would become elastic fluids. But many substances, as wa- 
ter, and alcohol, and even some solids, as camphor and ice, 
evaporate by mere exposure to the an*. In general, how- 
ever, when a sohd is converted into vapor by heat, the process 
is called suhlimation^ thus sulphur, and mercury, and some 
other solids are purified by sublimation, or dry distillation. 

We have already spoken of evaporation, chiefly as indu- 
ced by ebullition, but the subject has several other bearings 
which it will be well to illustrate and explain. 

69. Maximum density. — At a certain degree of heat there 
exists for the vapor of different s.ubstances a state of dens- 
ity which it cannot pass without losing its gaseous condi- 
tion, and becoming a liquid. This point is called its state 
of maximum density. When a volatile liquid is introduced 
in sufficient quantity into a vacuum, this condition is al- 
ways reached, and then evaporation ceases ; and any at- 
tempt to increase the density of this vapor by compressing 
it into a smaller space, will be attended by its liquefaction. 
Thus, if a little ether be introduced into a barometer tube, 
and the tube be slowly sunk into a deep cistern of mercury, 
it will be found that the height of the mercury in the glass 
will remain unaltered, until the upper extremity of the ba- 
rometer approaches the surface of the metal in the reservoir. 
It will be observed also, that as the tube sinks, the little stra- 
tum of liquid ether increases in thickness, but no increase 
of elastic force occurs in the vapor above it, and, conse- 
quently, no increase of density ; for tension and density, in 
elastic bodies, are always directly proportionate to each other. 

70. The point of maximum density of a vapor is depen- 
dent upon the temperature ; it increases rapidly as the tem- 
perature rises. Thus, taking the specific gravity of atmos- 
pheric air at 212 degrees to be 1000, then that of aqueous 
vapor in its greatest state of compression at different tempe- 
ratures will be as follows : — 

Temperature. Specific gravity. Weight of 100 cubic in. 

32 degrees. - - - - 5.590 .136 grains. 

50 " - - - 10.293 .247 " 

60 " 14.108 .338 " 

100 " 46.500 1.113 " 

150 " - - - 170.293 4.076 " 

212 " 625.000 14.962 " 

What is the difference between evaporation and sublimation? What i* 
meant by the maximum density of a gas ? 



40 THERMOMETER. 

Thus pressure, by increasing the density, may cause an 
elastic fluid to assume the hquid form ; and the same eflecl 
m many instances, is produced by cold, inasmuch as loss of 
heat depresses the point of maximum density. [See Lique- 
faction of the Gases.) 

THERMOMETER. 

71. The thermometer is an instrument founded on the 
principle that the expansion of matter is proportional to the 
augmentation of temperature, and is designed to measure the 
variations of heat and cold. 

72. The first attempt to measure such variations on this 
principle was made by Sanctorius, an Italian physician, in 
the seventeenth century. He emplo^^ed a glass tube, blown 
into a ball at one extremity, and open at the other. After 
expelling a small part of the air by heating the ball, the 
open end was plunged into a vessel of colored fluid, and as 
the air in the ball cooled, the fluid ascended up the tube. 
Any variation of temperature by expanding, or contracting 
the air in the ball, would then cause the hquid in the tube to 
rise or fall. An arrangement of this kind is represented at 
Fig. 7 

73. A better construction for an air ther- Fig. 13. 
mometer is represented at Fig. 1 3. It consists of 

a thin glass bottle, containing a small quantity of 
a colored liquid, and stopped closely by a cork. 
Through the cork is passed a broken thermometer 
tube, open at both ends. This tube descends 
nearly to the bottom of the bottle, and dips into 
the fluid. There is, therefore, a quantity of air 
above the fluid which cannot escape, and v/hen 
this expands by the application of heat, the fluid is 
forced up the tube. Thus the height of the fluid 
will indicate the expansion of the air, and conse- 
quently, the degree of heat to which the instru- 
ment is exposed. 

There are, however, two objections to the employment 
of air for this purpose. Its expansions and contractions are 
so great, even by small changes of temperature, that a tube 
several feet in length would be required to measure them ; 
and as air suffers condensation b}^ pressure, the variation 

On what principle is the thermometer constructed? Who first constructed 
ibermometers ? What fluid was first employed to indicate the variations of 
temperature ? Describe the construcdon of an air thermometer. What arc the 
objections to the air thermometers ? 



THERMOMETER 



41 



of the barometer would effect its height, at the same tem- 
perature. 

74. Differential Thermometer. — For the above reasons 
the air thermometer, for common purposes, is both incoji- 
venient and inaccurate, and therefore has long since been 
laid aside. There is, however, a modification of this instru- 
ment, invented by Mr. Leshe, and called the differential 
themiometer, which for certain purposes is a very elegant 
and useful instrument. 

A drawing of this instiiiment is represented 
by Fig. 14, and it is designed, as its name 
imports, to show the difference of temperature 
between two places at short distances from 
each other. It consists of a glass tube ter- 
minated at each end by a bulb, and bent as 
shown in the figure. The tube is partly filled 
with some colored fluid, as sulphuric acid, 
tinged with carmine, or alcohol, colored by 
cochineal, the bulbs and other parts of the 
tube being filled with air. 

It will be obvious, from the construction of 
this instrument, that it cannot indicate the 
temperature of the atmosphere, since an equal 
expansion of the air in both bulbs would press 
equally on the fluid in both legs of the tube, 
and consequently it would rise in neither. 
But if one bulb is exposed to a higher temperature than the 
other, then the expansion of the air in this, will be greater 
than in the other, and consequently the fluid will rise to- 
wards the bulb where the air is least expanded. 

75. Use. — The use of this thermometer, then, consists in 
showing the difference of temperature to which the bulbs 
are exposed, as in experiments on the radiation of heat, al- 
ready described. The scale affixed to one. of the legs, 
shows the rise in degrees, and is divided into 100 parts. 
The legs are six inches long, and the bulbs an inch or 
a little more in diameter. The stand may be of glass or 
wood. Some of these instruments are so delicate as to be 
affected by the approach of the hand. 

76. Air, being inapplicable to the construction of ther- 




How is the differential thermometer constructed, and for what purposes is 
it useful. Why will not the differential thermometer indicate the tempera 
ture of the atmosphere. 



42 THERMOMETEK. 

mojiieiers for the purpose of measuring the absolute temper- 
aturt^ of places or things, for the reasons already noticed, 
solid bodies are equally so from a contrary defect ; their ex- 
pansion by heat being so small as not to be appreciated with- 
out the adaptation of complicated machinery. A perfect 
substance for this purpose would be a fluid, which would 
expand uniformly with equal increments of heat, and which 
would neither freeze nor boil at any temperature to which it 
might be exposed. Mercury approaches nearer to these 
conditions than any other substance, and therefore this is the 
fluid now almost universally employed. 

77. The blowing of the best thermometer tubes requires 
much experience and skill in the workmen, and is per- 
formed only by particular artists. This is the most difiicult 
part of its construction. The mercury is introduced by 
heating the bulb, and thus rarefying the air within it, and 
then dipping the open end of the tube into a vessel of the 
fluid. As the air contracts within by cooling, the pressure 
of the external atmosphere forces the mercury to enter the 
tube to supply its place. When the bulb is nearly filled in 
this way, the mercury is boiled to expel the air. 

Having filled about one third of the tube, the open end is 
sealed hermetically, that is, by melting the glass. This is 
done while the mercury in the bulb is heated nearly to its 
boihng point, so as to exclude all the air. 

78. Having sealed the end of the tube, the next step in 
the construction of the thermometer, is its graduation. This 
is done by ascertaining two fixed and invariable points on the 
tube, which are the same in every thermometer, and then by 
making a scale of equal divisions between these two points. 
These are the freezing and boiling points. 

79. The freezing point is found by immersing the bulb of 
the thermometer in melting snow or ice, for it has been as- 
certained, that the temperature of water flowing from melt- 
ing snow or ice, is every where the same, whatever may be 
the heat of the atmosphere where the experiment is made. 
The boihng point is slightly affected by the pressure of the 
atmosphere ; but the thermometer will be sufficiently accu- 
rate for all ordinary purposes, when this point is ascertained 

Why are not solid bodies proper for the construction of thermometers ? 
What would be a perfect substance for the construction of thermometers? 
What is the most perfect fluid in our possession for this purpose ? How are 
thermometer tubes filled? How is the freezing point of the thermometer as- 
certained ? How is the boiling point ascertained? 



LIQUEFACTION OF THE GASES. 



43 



by iinmersmg the bulb in pure boiling water, open to the lu: 
and on the level of the sea, during pleasant weather. { Sf< 
Barometer, in Nat. Philosophy.) 

80. The freezing and boihng points are Fig. J 5 
marked with a diamond or file, on the tube ; /jOTN 
and on the scale to be afterwards affixed, the 
freezing point is marked 32, and the boiling 
point, 212. The. interval between these two 
points is then accurately divided into 180 equal 
parts. This is the divison of Fahrenheit's 
scale, the thermometer generally employed in 
this country, and is the only scale referred to 
in this work. 

The commencement of this scale is 32 de- 
grees below the freezing point, and is called 
zero., being marked with the cipher 0, to signify 
the total absence of heat. This degree of cold, 
it is supposed, Fahrenheit obtained by mixing 
snow and common salt, and it was probably 
the greatest degree of cold known in his time, 
though at the present day certain mixtures 
produce^ much greater, and at a future period, 
the progress of science may show the means of 
abstracting heat, so as to soHdify even the air we 
breathe. The absolute zero must therefore be 
considered an imaginary point. 

Besides the zero and the freezing and boil- 
ing points, marked on Fahrenheit's scale. Fig. 
15, there are also noted the temperature of the 
blood, and the heat of summer, and sometimes 
other points, as fever heat, &c. 



•w 



LIQUEFACTION OF THE GASES. 

81. The experiments of Mr. Faraday and others, on the li- 
quefaction of the gases, have resulted in the opinion that these 
aeriform bodies are nothing more than the vapors of extremely 
volatile liquids. Most of these liquids, if they are such, 
are naturally so volatile, that their boihng points, under the 
ordinary pressure of the atmosphere, are below the tempera- 
ture of the coldest regions of the globe, and hence they are 
always found in the gaseous state. But by subjecting seve 



V/hat opinion exist.s about the form of the gases ? What is the reason 
that the gases do n«t retain their liquid states? 



44 LIQUEFACTION OF THE GASES. 

rai of 'hem lo great pressure, their gaseous condition is so 
fur counteracted as to make them form hquids, and in onf< 
instance, even a soHd. Even when so compressed, a very 
small additional heat will make them boil, and the instant 
the pressure is removed, they again assume the elastic form, 
and some of them, with such violence as to cause an explo- 
sion of more or less intensity. This sudden change of a 
solid, or liquid, into the elastic state, in consequence of 
changing the heat from a sensible to a latent condition, pro- 
duces a remarkable degree of cold. 

82. Process for condensing the gases. — The method of 
condensing the gases consists in exposing them to the 
pressure of their own elasticity, or their own atmospheres. 
The process is exceedingly simple, and may be performed 
bv any one, though without care and experience, it may be 
attended with much danger to the experimenter. 

83. The materials to 

form the gas are put ^^S- ^^• 

into a strong glass tube, 

Fig. 16, bent as in the 

figure, after which the 

orifice is hermetically 

sealed, or closed by means of a metalhc cap with some 

strong cement. In most instances, it is necessar}'- that 

the materials should be kept apart, until the tube is closed, 

after which, by a change of position, they are brought 

to act on each other. Thus, for carbonic acid gas, some 

dilute sulphuric acid is poured into the tube, and at the 

other end is placed some pieces of chalk or marble, and 

after the orifice is closed, by changing the position of the 

tube they are brought together, when the gas is instantly 

evolved. 

84. The amount of pressure required to liquefy the dif- 
ferent gases, is quite variable. Thus, sulphuric acid gas 
requires only 2 atmospheres at 45 degrees; carbonic acid 
gas 36 atmospheres at 32 degrees, while nitrous oxide gas 
does not become liquid at a less pressure than 50 atmos- 
pheres. 

In what maimer may the gases be made to assume the liquid form? 
Describe the apparatus and process of condensing the gases? Do all 
the gases require the same amotmt of pressure for their liquefaction? 
What gas requires the least and what the greatest pressure for thi.s purpose? 
What is the amount of pressure whif'h nitrous oxide recjuires for its li(iue- 
"action ? 




COLD. 



45 



Now, taking the pressure of the atmosphere to be equal 
to 15 pounds to the square inch, and the size of the 
tube on the inside equal to an inch square, then the force 
on the tube in which nitrous oxide becomes hquid, would 
be (provided the tube be eight inches long) equal to 6,000 
pounds, for 15 lbs. x 50 atmospheres = 750, which x by 8 
inches long = 6,000. 

85. Carbonic acid is the only gas which has been re- 
duced to the sohd form. To prepare this, a very strong 
metallic apparatus is required, involving considerable ex- 
pense, and perhaps not a little difficulty to those not in the 
practice of making chemical experiments. When prepared 
if a small jet be permitted to escape by the turnino- of a 
stop-cock, the most intense action inslantly follows at- 
tended by such a degree of cold as actually to freeze the 
portion which has not made its escape from the vessel 
When frozen, it has the appearance of fine moist snow, 
which being exposed to the air soon evaporates, but if cov- 
ered with cotton, may be preserved in the solid state for hours. 

86. In some instances heat is required in order to sepa- 
rate the gas from its combinations, after which the process 
of liquefaction is greatly facilitated by cold. This is pro- 
duced by surrounding the vessel containing the gas with 
pounded ice, or snow, mixed with common salt. 

COLD, 

87. Cold is a negative condition, and depends on the ab- 
sence, or privation of heat. Intense artificial cold may be 
produced by the rapid absorption of heat during the conver- 
sion of solids into hquids. Dr. Black long since discovered 
the principle, that when bodies pass from a denser to a rarer 
state heat is absorbed and becomes latent in the body so 
transformed, and consequently cold is produced. And also 
that when bodies pass from a rarer to a denser state, their 
latent heat is evolved, and becomes sensible. 

It is known to almost every one, that dissolving common 
salt m water, particularly if the salt is fine, will lender the 

.!!',^.l p!^!"^!".k"^ .^.''!',^ carbonic acid exhibit in the solid state? What 




,,u,,u ui nv dUMji ue zero Known ! What is cold? How mav intense irtJ 
fic.al cold be produced ? When bodies pass from a denser to a rarer s^ate' 
js heat or cold produced ? How is the temperature of water genLfh knmvn 
to oe affected by dissolving common salt in it ^ genoraiiv Known 



46 COLD. 

water so cold, even in summer, as to be painful to the hand 
The salt, as it passes from the solid to the liquid state, ab- 
sorbs caloric from the water, and thus the heat that was 
before sensible, becomes latent, and cold is produced. 

88. On the contrary, when a piece of lead, or iron, is beaten 
smartly with a hammer, it becomes hot, because the metal, 
in consequence of the hammering, has its capacity for calo- 
ric reduced, and thus the heat which was before latent, now 
becomes sensible. For the same reason, when air is com- 
pressed forcibly in a tube, or as it is sometimes called, in a 
-fire-pump^ as already explained, the heat, which was before 
latent, becomes sensible, because the condensation lessens 
its capacity for caloric. 

89. The principle on which all freezing mixtures act, is 
therefore the change of state which one or more of the arti- 
cles em.ployed undergo, during the process, and this change 
consists in an enlarged capacity for caloric. The degree 
of cold will then depend on the quantity of caloric which 
passes from a free to a latent state, and this again will de- 
pend on the quantity of substance liquefied, and the rapidity 
of the liquefaction. 

90. The substances most commonly employed for this 
purpose are those originally used by Fahrenheit, to produce 
the zero of his thermometric scale ; viz. common salt and 
snow, or pounded ice. For this purpose the salt should be 
fine, and the ice, which must always be used in summer, is 
to be reduced to small particles in a cold mortar. 

91. The vessel to contain the substance to 

be frozen may be made of tin, and of the Fig. 17. 
shape represented by Fig. 17. It is simplj'- 
a tall vessel, holding a few pints, with a close 
cover, and a rim round the top, for the con- 
venience of handHng it. For common pur- 
poses, this may be set into any convenient 
wooden vessel, (having first introduced the 
substance to be frozen,) and then surrounded 
by the freezing mixture. The only care to 
be taken in this part of the process is, to see 
that the freezing mixture in the outside ves- 
sel reaches as high as the contents of the in- 
ternal one. With two or three pounds of 



How is this change of temperature accounted for ? Why does a piece of 
iron become hot by hammering ? 




GOLD. 47 

fine common salt, and double this weight of pounded ice, 
three or four pints of iced cream may be made in this way, 
during the warmest days of summer. The process requires 
two or three hours, and while it is going on, the vessel 
should be set in a cellar, or covered with a flannel cloth, as 
a bad conductor of the external heat. 

92. When the therniometer is at 32 degrees, the cold 
generated by the above process sinks it down to zero, as 
above stated. By this method, two solids are changed into 
liquids, and both during the change absorb caloric from the 
contents of the inner vessel. The salt melts the ice in con- 
sequence of the avidity with which it imbibes moisture, or 
by reason of its affinity to water, and the water in its turn 
dissolves the salt. 

93. Other substances, having a stronger affinity (see 
Affinity) for water than common salt, will produce the same 
effects still more powerfully. Thus, muriate of lime (see this 
article) five parts, and ice four parts, will sink the ther- 
mometer from 32 degrees to 40 degrees below zero, that is, 
in the whole, 72 degrees. At this temperature, mercury 
freezes. A still more effective mixture is four parts of fused 
potash, and three parts of snow. This is said to sink the 
mercury from 32 degrees to 50 degrees below zero, that is, 
82 degrees. In these experiments the thermometers are 
filled with alcohol, instead of mercury. 

94. Freezing mixtures are also made of a solid and a 
fluid. One of the most effectual of this kind is composed of 
diluted sulphuric acid and snow, or pounded ice. This 
sinks the mercury from 32 degrees to 23 degrees below 
zero. 

Though ice or snow is commonly employed for this pur- 
pose, still powerful frigioric effects may be produced without 
either, the absorption of caloric being caused by the rapid 
solution of a salt in a fluid. One of the most common and 
cl|eap among these is a mixture of sulphate of soda or Glau- 

How do you account for the heat evolved, where air is compressed ? What 
is the principle on which freezing mixtures act? On what circumstance 
will the degree of cold produced by freezing mixtures depend ? What are 
the substances most commonly used as freezing mixtures? Explain Fig. 17, 
and show how it is to be used ? How far below 32 degrees will a mixture of 
ice and common salt sink the thermometer? Wliy does the salt melt the ice ? 
What substance sinks the thermometer from 32 to 40 degrees below zero ? 
In these experiments, why is alcohol used to fill the thermometer, instead 
of mercury? What is said of sulphuric acid and snow, as a freezing mix- 
ture ? 



48 SOURCES OF CALORIC. 

ber's salt, and diluted sulphuric acid. This sinks the mer- 
cury from 50 degrees to 3 degrees above the freezing point, 
that is 47 degrees. 

95. In describing experiments of this kind, it should al- 
ways be noted from what point the thermometer begins to 
descend, otherwise no judgment of the power of the freezing 
mixture can be formed. If, for instance, a mixture would 
cause the depression of the thermometer from, and below any 
given point, then by repeating the process continually, we 
should be able to find the absolute zero. Thus, by means 
of muriate of lime and snow, the thermometer is made to 
sink 82 degrees, that is, from 32 degrees above, to 50 de- 
grees below zero. Now, if the same cause would again 
produce the same effect, by its re-application, the thermome- 
ter would sink to 132 degrees below zero, a degree of cold 
never yet produced by any means. But an unhmited de- 
gree of cold can never be produced by the art of man : for 
it is found on experiment, that when the temperature pro- 
duced by the freezing mixture is greatly below that of the 
air, the caloric is so rapidlj^ communicated, as to prevent 
any effect by repeating the process. Mr. Walker, who 
made a great number of experiments on this subject, was 
never able to produce a greater degree of cold than that of 
100 degi'ees below the zero of Fahrenheit. 

SOURCES OF CALOfllC. 

96. The sources of caloric may be reduced to six, viz. 
The Sun, Combustion, Electricity, the bodies of living 
warm-blooded animals. Chemical action, and Mechanical 
action. 

The Sun constantly radiates caloric to the earth, and is 
the great fountain of heat to us and to the whole solar 
system. 

97. Combustion. — This supplies the heat employed in the 
arts, and for culinary purposes. In this process the caloric 
is extricated from the oxj^gen of the atmosphere, as it unites 
with the burning body and supports its combustion. The 
light is supposed to be furnished by the burning body. 

What substances form a freezing mixture without the use of ice oi 
snow? In malving experiments with freezirt^ mixtures, why is it necessary 
to state the degree from which the thermometer begins to fall ? What is the 
reason that an unlimited degree of cold cannot be produced by art? What 
is the greatest degree of cold ever produced ? What are the sources of ca 
loric? What is the great fountain of heat? How is heat extricated by com 
bustion ? 



SOURC.KS OF CALORIC. 49 

93. Electricity. — Whenever two bodies in opposite elec- 
trical states are made to approach each other, so as to pro- 
duce a discharge through the air, or along a non-conductor, 
there appears a flash of light, attended by heat. By the 
action of Galvanism, which is a modification of electricity, 
the most intense heat hitherto known has been produced. 

When the electric fluid passes through a piece of metal, 
or other conductor, of sufficient size, no phenomena are pro- 
duced; but in its passage through a non-conductor, or 
through a conductor which is too small to admit of a free 
passage, heat is produced. [See Electricity, in Natural 
Philosophy. ) 

99. Vital action. — The bodies of air-breathing animals are 
a continual source of heat. The numerous theories which 
have been invented to account for the cause of animal heat 
cannot here be investigated. That it however depends on 
the oxygen of the atmosphere which we breathe, seems to 
be proved by the fact, that animal warmth cannot for any 
length of time be sustained without it. 

100. Chemical action. — Chemical action without combus- 
tion is capable of producing considerable degrees of heat. 
If water be thrown on unslacked quicklime, in small quanti- 
ties at a time, its heat will be gradually augmented to 
nearly 1000 degrees, or so as to ignite wood. The heat in 
this experiment is accounted for, on the law already ex- 
plained, that Avhen bodies pass from a rarer to a denser 
state, caloric is evolved. The slacking lime absorbs the 
water and retains it as a part of its substance, and thus a 
fluid is converted into a sohd, with the evolution of much 
caloric. 

If three parts of strong sulphuric acid and one of water 
be suddenly mixed together, a degree of heat considerably 
above that of boiling water will be produced. In this case 
the heat is also accounted for on the principle of condensa- 
tion, for if the two fluids be measured before and after mix- 
ture, it will be found that their union has occasioned a loss 
of bulk, and probably also a loss of capacity for caloric. 

The inflammation of spirit of turpentine by nitric acid 
is a case of intense chemical action, in which 1000 degrees 

When does electricity produce heat? What is the cause of electrical 
heat, according to Sir H. Davy ? What is said of vital action, as a cause 
of heat? What is said of chemical action as the cause of heat? How is 
the heat produced by throwing water on (juicklime accounted for ? When 
aulohuric acid and water are mixed, what is the cause of the heat produced? 

3 



5U SOURCES OF CALORIC. 

of neat are evolved. About an ounce of the turpentine, with 
the same weight of nitric, mixed with a httle sulphuric 
acid, are the proportions. I'he acid should be poured on 
the turpentine from a vessel tied to a rod several feet long, 
as the explosion sometimes throws the burning matter to a 
considerable distance. 

101. Mechanical action. — This includes percussion^ fric 
tion, and condensation. 

Caloric is evolved by the percussion of hard bodies 
against each other. This is owing to the condensation of 
the body struck, in consequence of which its latent heat 
becomes sensible. 

If a piece of soft iron be struck smartly several times with 
a hamm^er, on an anvil, it becomes hot, and even red hot, 
if the experiment be well conducted. 

When a piece of steel and a flint are struck together, the 
condensation produces so much heat as to set fire to the 
small particles of steel which at the same time are struck 
off by the blow. 

102. Friction. — Caloric is evolved, or produced by fric- 
tion. The friction of machinery, when the motion is rapid, 
frequently causes so much heat as to set the wood on fire. 
The inhabitants of various nations obtain fire by nibbing 
pieces of dry wood together. The friction of carriage 
wheels sometimes sets them on fire. 

The principle on which caloric is produced by friction has 
not been demonstrated. It cannot be referred to condensa- 
tion, since the rubbing of two soft bodies together, such as 
the hand against the coat-sleeve, or the two hands against 
each other, causes heat. 

Count Rumford, who made a laborious and varied course 
of experiments on this subject, w^as led to the conclusion that 
the heat produced by friction could not be connected with 
the decomposition of oxygen gas, nor with the increase of 
density, nor could it be caused by any change in the specific 
caloric of bodies. Others have also made experiments with 
a view to determine this question, but as yet no one has pre- 
tended to give any satisfactory explanation of its cause. 

103. The Condensation of an elastic fluid by sudden 

How may spirits of turpentine be inflamed by chenical action ? What 
does mechanical action, as a source of heat, include ? How is the evolution 
of heat by percussion accounted for ? When a piece of steel is struck by a 
flint, how is the fire produced ? How is the heat produced by ^riclion ac- 
counted for'' How does condensation produce heaf 



LIGHT. 



51 



pressure causes heat, as has already been explained, and 
illustrated by Fig. 1 1. The heat evolved in this case arises 
simply from the diminished capacity of the air for caloric, 
in consequence of its increased density. 



1 04. The next imponderable agent which falls under our 
notice is light. The investigation of the properties of 
light,— its laws of reflection and refraction, and its effects on 
the sense of vision, are subjects belonging to the science 
of Optics. (See Optics in Nat. Philosophy.) Some of the 
effects of light are however properly considered here, since 
they produce chemical phenomena. 

Light may be decomposed, by means of a prism, into 
seven primary colors. The succession of these colors, 
beginning with the uppermost, is violet, indigo, blue, green^ 
yellow, orange, red. 

The decomposition of light, only requires that a ray 
should be admitted through a small aperture into a room, 
and made to pass through a triangular prism, as represented 
by Fig. 18. 

The direction of Fig. 18. 

the ray towards the 
point c will be 
changed by the re- 
fractive power of 
the prism, and at 
the same time it will 
be decomposed into 
the colors already named, the violet corresponding with 1, 
and the red with 7. It may be observed by the figure, that 
the red is refracted least, and the violet most, from the 
direction of the original ray, these two colors terminating 
the under and the upper parts of the spectrum. 

These seven are called the primary colors, since they 
cannot by any known means be again decomposed, or sepa- 
rated into other colors. The whole seven are called the 
solar spectrum. 




To what science does the investigation of the properties of light, with its 
eflfects on the sense of vision, belong ? Why do some of the effects of light 
properly belong to the investigations of chemistry ? Into how many primary 
colors may light be divided ? What is the succession of these colors, be 
ginning with the uppermost? How may the decomposition of light bt 
effected ? Which ray is most, and which is least refracted, from the direc 
tion of the original ray ? What are these seven colors called ? 



52 UGirv. 



105 The heating powers of these several colors are dif- 
feient. Take a sensible air thermometer (Fig. 13) and move 
the bulb in succession through all the colored rajs, waiting 
at each for the fluid to rise, or fall. The thermometer will 
be found to indicate the greatest heat in the red ray, next in 
the green, and so on, in a diminishing ratio, to the violet. 

When the thermometer is moved a little beyond the red 
ray, but in a line with the spectrum, the heat is still greater 
than in the ray itself These heating rays are invisible to 
the eye, and hence it is concluded that there exists in the 
solar beam a distinct ray which causes heat, but no light. 

The illuminating power of each primary ray in the solar 
spectrum, is different from the other. This is proved by 
permitting the spectmm to fall on a large printed sheet, of 
the same sized type, when it will be found, that at the same 
distance, the parts illuminated by some of the rays can be 
read, while those illuminated by others are indistinct. 

Light is capable of being absorbed by certain substances, 
of remaining in them for a time, and then of being extricated 
unaltered. Such bodies are called solar phosphori. 

106. Photometer. — This term signifies "light measurer," 
and was invented by Dr. Leslie for the purpose of ascer- 
taining the comparative intensities of light. It consists 
merely of a diflferential thermometer (Fig. 14.) with one of 
the balls elevated above the other, and left transparent, as 
usual, while the other ball is made of black glass, or is 
covered with India-ink. The clear ball transmits all the 
rays both of heat and light which fall upon it, and there- 
fore its temperature is not affected ; on the contrary, they 
are all absorbed by the black ball, and by heating and ex- 
panding the air within, causes it to press upon the colored 
liquid, which ascending towards the clear ball in the opposite 
stem, indicates the degrees of light to which it is exposed. 
The whole instrument is covered with a case of thin glass 
to protect it from currents of cool air. 

It will be observed that the action of this photometer 
depends on the heat which the black ball absorbs from the 
light to which it is exposed. 

What are the whole called? What is said of the heating powers of the 
different rays? Is the greatest heating power in the red ray, or beyond it? 
Are the heating rays visible, or invisible? How is it proved that the illumi- 
nating powers of the different rays differ ? What is the meaning of the 
word photometer ? In what manner is it constructed ? In what manner is it 
used? 



1 



PHOSPHORESCENCE. 53 

PHOSPHORESCENCE. 

107. Phosphorescence may be defined, the emission of 
light without sensible heat, or witliout combustion. 

A considerable number of substances have the power of 
absorbing a quantity of light when exposed to the rays of tne 
sun, and of emitting it again, so as to become luminous in 
the dark. Most substances lose this property in a short time, 
but acquire it again by another exposure to the sun, and this 
may be repeated any number of times. Several substances 
by this treatment become so luminous as to render minute 
objects visible in the dark. Canton's phosphorus is of this 
kind, and may be prepared as follows : Calcine common oys- 
ter sheUs in the fire for an hour ; then select the purest and 
whitest parts, and reduce them to fine powder. Mix three 
parts of this powder with one of sulphur, and having pressed 
the mixture into a crucible, keep it red hot for one hour. 
Then let the crucible cool, and select the brightest and purest 
parts, which cork up in a dry vial for use. 

When this composition has been exposed for a few minutes 
to the fight of the sun, and then carried into the dark, it 
will be sufficiently luminous to show the hour by a watch 
dial. 

The same property is possessed by compositions called 
Romberg's and Baldwin's phosphorus. The diamond, also, 
possesses this property, as shown by the celebrated experi- 
ment of Dufay, who, having exposed a diamond to the 
light, immediately covered it with wax, and on removing the 
wax, several months afterwards, found that it shone in the 
dark. 

108. Some substances phosphoresce by friction, some by 
scratching, and i3thers by heat. 

That variety of carbonate of lime called dolomite, gives 
light on being rubbed. Loaf sugar mixed with whites of 
eggs and dried, as is done for the frosting of cake, emits a 
streak of light on being scratched with a sharp point. Several 
varieties of fluate of lime, and of marble, emit fight when 
coarsely powdered and thrown on a hot plate of iron, so as 
to be seen in the dark. 



What is phosphorescence ? What are solar phosphor! ? What is said of 
the power of bodies to absorb and eniit light ? What is Canton's phosphorus ? 
How is Canton's phosphorus prepared? What is necessary in order to make 
this substance shine in the dark ? How did Dufay confine the ligh« in a 
diamond? What is said of the phosphorescence of other substances^ 



54 PHOSPHORESCENCE. 

A piece of tobacco pipe, or a piece of quicklime, when 
heated hy the compound blowpipe, or bj other means, to a 
degree which would only make other bodies red, give out 
a brilHant phosphorescent light, which is so intense as to 
become intolerable to the eyes. 

109. Another kind of phosphorescence may be observed 
during the decomposition of certain animal substances. 
Thus, if a small piece of fresh hening, or mackerel, be put 
into a two ounce vial of sea water, or into pure water, with 
a little common salt, and the vial be kept in a warm place 
for two or three daj^s, there will then appear a luminous 
ring on the surface of the water, and if the vial be shaken, 
the whole will give a phosphorescent light. 

110. Light produces very material effects on the growth 
of all vegetables, from the most humble plant, to the tallest 
tree of the forest. Plants vegetating in the dark are white, 
feeble, almost tasteless, and contain but little combustible or 
carbonaceous matter. On exposing such plants to the light 
of the sun, their colors become green, their tastes become 
much more intense, and the quantity of their combustible 
matter becomes greatly increased. These changes are 
strikingly obvious, and, beyond all doubt, depend on the 
agency of hght. 

111. Light not only affects the natural, but, in many in- 
stances, the artificial colors of things. In this respect, how- 
ever, its effects appear not to be reducible to any general 
law, for in some instances it destroys, and in others it aug- 
ments, or even creates the colors of bodies. 

On exposing bees wax to the sun and moisture, its color 
is discharged, and it becomes white ; it is also well known 
that the colors of printed goods, and of carpets, are changed, 
or faded by the same influence ; and that the former mode 
of bleaching, consisted in exposing the cloth to the united 
influence of hght, air, and moisture. 

112. On the contrary, the colors of plants appear to be 
exclusively owing to their exposure to hght; and various 
chemical preparations, such as phosphorus, and the nitrate 
and chloride of silver, become dark colored, and even blacky 
by the influence of light. 

What is said of the phosphorescence of a piece of tobacco pipe, or quick 
lime? How may a piece of fish be made to exhibit phosphorescence'. 
How are plants affected by growing in the dark? What changes ar*. 
effected by the light of the sun on plants which have grown in the dark t 
How are the artificial colors of things aflfected by light? To what do tho 
colors of plants appear to be entirely owing? What substaaces become dark 
colored by the influence of light ^ 



ELECTRICITY. 55 

113. Light has also an important and curious influence 
on the crystallization of salts. Make a strong solution of 
the sulphate' of iron, in water, and place it in a shallow dish. 
Cover one half of the dish with a black cloth, and set it in 
a darkened room, permitting only a single ray of light to 
enter, so as to strike upon the solution in the uncovered part 
of the dish. Thus one half of the solution will be exposed 
to the Hght, while the other half will be in darkness. After 
the dish has stood in this situation for a day or two, it will 
be found that no signs of crystallization are to be seen in 
that part of the solution which has been kept in the dark, 
while that part which has been exposed to the light will be 
completely crj^stallized. 

1 14. Another curious fact connected with this subject is, 
that plants emit oxygen gas through the influence of the 
sun's light. To make this obvious, fill a tall glass vessel, 
such as a bell glass, with water, and invert it into another 
vessel of water. Then introduce into the bell glass some 
sprigs of mint, or any other plant of vigorous growth, and 
expose the whole to the action of the sun. Small bubbles 
of air will soon appear, as though issuing from the leaves 
of the plant. These will, one after another, detach them- 
selves, and arise to the upper part of the vessel, and, on ex- 
amination, the air thus extricated will be found to consist 
of very pure oxygen gas. {See Oxygen.) 

115. In this experiment, the water serves only as the 
means of collecting the oxygen, the water itself not being 
decomposed by the plant, but only the air which it contains. 
The air which we breathe contains a quantity of carbonic 
acid, which is decomposed by ne organs of the plant, the 
carbon being retained, while tl ; oxygen is emitted. {See 
Vegetation.) 

ELECTRICITY. 

116. The third imponderable agent is Electricity, inclu- 
ding Galvanism. 

The ancients knew nothing of electricity as a science. 
They knew, indeed, that amber and glass, when rubbed, 
would attract light substances ; and about the beginning of 
the eighteenth century, it was discovered that a certain 



How is it shown that light has an influence on the crystallization of salts? 
How is it demonstrated that plants emit oxygen gas through the influence of 
the sun's light ? Describe the chemical changes by which plants extricat* 
oxygen gas 1 Was electricity known to the ancients as a science T 



56 ELECTRICITY. 

stono. called tourmaline, would attract feathers and hair, 
when heated, and that some precious stones would do the 
same when rubbed. As an important science, electricity 
can claim no higher date than the age of FrankHn. 

117. Galvanism is of much more recent date than elec- 
tricity. This science owes its name and origin to an acci- 
dental discovery made by Galvani, an Italian, in 1791. 
Galvani was professor of anatomy at Bologna, and his great 
discovery seems to have been owing, indirectly, to the sickly 
condition of his wife. This lady, being consumptive, was 
advised to take soup made of the flesh of frogs, as the most 
delicate nutriment. One of these animals, ready skinned, 
happened to lie on a table in the professor's laboratory, near 
which stood an electrical machine, with which a pupil was 
making experiments. While the machine was in action, 
the pupil chanced to touch one of the legs of the frog with 
a knife which he held in his hand, when suddenly the dead 
animal was thrown into violent convulsions. This singular 
circumstance excited the attention of the sick lady, who 
was present, and it was communicated to her husband, who 
was out of the room at the time. Galvani immediately re- 
peated the experiment, and soon found that the convulsions 
took place only when a spark was drawn from the elec- 
trical machine, the knife at the same time touching the 
nerve of the frog. He also ascertained, from further inves- 
tigations, that the same contractions were excited without 
the agency of an electrical machine, provided he employed 
two metals, such as zinc and silver, one of which was made 
to touch the nerve, while ae other touched the muscle of 
the frog. [See Galvanism It is from such a beginning, 
that the now important scit ace of galvanism had its origin. 

118. Electricity, as an agent, is considered as an ex- 
ceedingly subtle fluid, so hght as not to affect the most 
delicate balances, — moving with unmeasurable velocity, 
and pervading all substances. It is, therefore, its eflects on 
other bodies only, or its phenomena, which it is in our power 
to examine. 

119. The simple facts on which the whole science of 
electricity is founded, may be stated in a few words. 

What is the date of electricity as a science? To what circumstance does 
galvanism owe its origin ? What is said of electricity as an agent ? Is it 
in our power to examine electricity as a substance ? How are we enabled 
to examine the properties of this agent? Describe the simple phenomena 
of electricity. 



ELECTRICITY. 57 

11 a piece of glass, amber, or sealing-wax, be rubbed with 
the dry hand, or with flannel, silk, or fur, and then held 
near small, light bodies, such as straws, hairs, or threads, 
these bodies will flj' towards the glass, amber, or wax, thus 
rubbed, and, for a moment, will adhere to them. The sub- 
stances having this power of attraction are called electrics^ 
and the agency by which this power is exerted, is called 
electricity. Some bodies, such as certain crystals, exert the 
same power when heated, and others become electric by 
pressure. 

120. Although these are the simple facts on which the sci- 
ence is based, yet electricity exhibits a vast number of curious 
and interesting phenomena, depending on the 

variety and kind of machinery, and the quantity ~ 
of the electrical influence employed. 

121. When a piece of glass, or other electric, 
has been rubbed, so as to attract other bodies, it 
is said to be excited., and it is found that many 
substances are capable of this excitement, when 
managed in a pecuhar manner. 

122. The most common are amher, glass, 
rosin, sulphur, wax, and the fur of animals. 
When an excited electric is presented towards a small ball, 
made of pith, or cork, and suspended by a string, (Fig. 19,) 
the ball is attracted to the electric, and adheres to it for a 
moment. And if two such balls be sus- 
pended so as to touch each other, and the 
excited electric be made to touch one of 
them, the other will instantly recede froni 
the one so touched ; that is, they will mu- 
tually repel each other, and remain for a 
short time in the position shown by Fig. 
20. If, while they are in this position, one 
of them be touched with the finger, or a 
piece of metal, they will again instantly attract each other, 
and come together; and, if suspended apart, will approach 
each other, as represented by Fig. 21. 





What are electrics ? What is electricity ? By what process, besides 
friction, do some bodies become electric ? When is an electric said to bo 
excited "^ What are the most common electrics ? What effect does an ex- 
cited electric produce on a suspended pith ball ? What is the effect on two 
pith balls in contact? When the balls are thrown apart by repulsion, what 
efiect is produced by touching one of them with the finger ? 

3* 




68 <':lectricity. 

123. In the explanation of these phenomena, Fig. 21- 
we suppose that all bodies are pervaded with the 
electric fluid, but that when in equilibrium, like 
air and water, it produces no obvious effects, and 
that it is only when this equilibrium is disturbed, 
or when some bodies contain more of the fluid 
than others, that electrical effects can be pro- 
duced. 

When an electric is rubbed with the hand, or other ex- 
citing substance, it receives a portion of the electric fluid 
from that substance; consequently, the electric then has a 
greater portion of electricity than is natural, while the hand, 
or other substance, has less. When two bodies are in dif- 
ferent electrical states, that is, when one has more or less 
than the natural quantity, they attract each other. This is 
illustrated by Fig. 19, where the ball is represented as 
moving towards the excited electric. 

124. But when two bodies have each more or less than 
the natural quantity, they repel each other. This is illus- 
trated by Fig. 20, where the repulsion is caused by the 
communication of an uncommon share of the fluid from the 
excited electric to one ball, and from this, ball to the other, 
and thus the two balls have more than their ordinarj^ quan- 
tity of electricity, and are in the same electrical state. 

On touching one of the balls with the finger, they again 
attract each other, because the finger deprives this ball of a 
part of its electricity, while the other ball is not affected, and 
thus the two balls are thrown into different electrical states. 
This is illustrated by Fig. 21. 

125. Theory of Electricity. — To account for electrical 
phenomena. Dr. Franklin supposed, as above stated, that all 
terrestrial things had a natural quantity of that subtle fluid, 
but that its effects became apparent, only when a substance 
contained more or less than the natural quantity, which 
condition is effected by the friction of an electric. Thus, 
when a piece of glass is rubbed by the hand, the equili- 
brium is lost, the electrical fluid passing from the hand to 

Explain these phenomena. Are all bodies supposed to be pervaded by the 
electrical fluid ? Suppose an electric is rubbed by the hand, does it, in con- 
sequence, contain more or less electricity than before ? Whence does the 
electric obtain this additional quantity of electricity? Wlien do bodies 
attract each other through the influence of electricity ? When do bodies 
repel each other through this influence? When the balls are thrown apart 
by repulsion, why do they attract each other on touching one of them with 
the fmger? 



ELECTRICITY. 59 

the glass, so that now the hand contains less, and the glass 
more, than their ordinary quantities. These two states he 
called positive and negative^ implying the presence and ab- 
sence of the electrical fluid. If now a conductor of electri- 
city, such as a piece of metal, be made to touch the positive 
body, or is brought near it, the accumulated fluid will leave 
this body and pass to the conductor, which will then con- 
tain more than its natural quantity of the fluid. But if the 
conductor be made to touch a negative body, then the con- 
ductor will impart a share of its own natural quantity of the 
fluid to that body, and consequently will contain less than 
ordinary. Also, when one body, positively, and the other 
negatively electrified, are connected by a conducting sub- 
stance, then the fluid rushes from thepo'sitive to the negative 
side, and the equilibrium is restored. 

This theory, originally invented by Dr. Franklin, will 
account satisfactorily for nearly every electrical phenomenon. 
There is, however, another theory, that of Dufay, which is 
still embraced by some writers. 

126. Dufay'' s theory. — This theory supposes that there 
are two kinds of electricity, which are termed the vitreous 
and resinous^ corresponding with the positive and negative 
of Franklin. This is founded on the fact, that when two 
pith balls, or other light bodies, near together, are touched 
by an excited piece of glass, or sealing wax, they repel each 
other. But if one of the balls be touched by the glass, and 
the other by the wax, they will attract each other. Hence 
Dufay concluded that electricity consists of two distinct 
fluids, which exist together in all bodies : that these two 
fluids attract each other, but that they are separated by the 
excitation of an electric, and that when thus separated, and 
transferred to non-electrics, as to the pith balls, the mutual 
attraction of the two electricities causes the balls to rush 
towards each other. 

The electricity corresponding with the positive of Frank- 
lin, is called vitreous, because it is obtained from glass ; 
while the other is called resinous, because it is obtained from 
wax and resin. 



How are these phenomena accounted for on Dr. Franklin's theory ? What 
are the positive and negative electrical states ? Does Dr. Franklin's theory 
account for most of the phenomena observed? What do the positive and 
negative states imply ? How does Dufay's theory differ from Franklin's ? 
How do the vitreous and resinous electricities of Dufay correspond with the 
positive and negative of Franklin ? 



60 ELECTRICITY. 

In rnspect to the merit of these two theories, we can OT\]y 
say here, that Frankhn's is by tar the most simple, and ac- 
counts equaUy well for nearly every electrical phenomenon. 

1'27. Conductors of Electricity. — Some bodies permit the 
electrical fluid to pass through them without difficulty. 
These are called conductors. They are the metals, water, 
and other 5uids, except the oils, steam, ice, and snow. The 
best conductors are gold, silver, platina, brass, and iron. 
The con^'uctors are non-electrics, that is, they show no signs 
of excitement when rubbed, under common circumstances. 
The electrics are non-conductors, that is, they will not con- 
duct the electric fluid from a negative to a positive sub- 
stance, and when excited, this fluid accumulates on their sur- 
faces, because they have not the power of conducting it 
away. A body is said to be insulated, when it is supported 
by a non-conductor. A man standing on a stool supported 
by glass legs, or standing on a cake of wax, is insulated. 
When one body, or system of bodies, is in the positive state, 
the other part, or system, being contiguous, is invariably in 
the negative state. If one end of a stick of sealing-wax, or 
glass rod, be positive, the other end will be negative, and if 
ore side of a plate of glass be positive, the other side will be 
negative. {See Electricity in Nat. Philosophy.) 

CHEMICAL EFFECTS OF ELECTRICITY. 

128. The chemical effects of electricity are most con- 
spicuous in that form of this agency known under the name 
of Galvanism, but there are many instances in which com- 
mon electricity produces important chemical changes. 

129. When powerful electrical discharges are passed 
through a glass tube containing pure water, by means of a 
gold or platina conductor, the water is decomposed, and re- 
solved into its two elements, hydrogen and oxygen, {see these 
articles,) which immediately assume the 

gaseous form. If afterAvards the gaseous Fig. 22. 

mixture thus obtained be submitted to elec- ^ ^ 

trical shocks, the re-union of these elements 
will again be effected, the hydrogen will ^ 
be inflamed, while its combustion will be 
supported by the oxygen; the gaseous 
mixture will entirely disappear, and water 
will be formed. 

The method of performing this experi- 
ment is shown by Fig. 22, where a repre- 



ELECTRICITY. 61 

sents a glass tube containing the two gases, and Z>, r, the two 
elecrrical conductors, the points of which approach so iic ar 
as to permit the fluid to pass through the gases, from one 
point to the other. 

To explain the phenomena of the decomposition of the 
water by electrical agency, we have to suppose that the two 
gases are naturally in opposite states of electricity, but that 
when united to form water, the electricity is in a state of 
equilibrium. When, therefore, water is submitted to the 
power of this agent, this equilibrium is destroyed, the nega- 
tive gas, or oxygen, passing to the positive conductor, while 
the hydrogen, being in a positive state, passes to the nega- 
tive conductor. Thus the fluid is decomposed, and assumes 
the gaseous form of its constituents. 

The union of the two gases, and the consequent re-com- 
position of water, is simply in consequence of the heat 
evolved by the electrical shock, as it passes through them. 
A degree of heat, by any other means, suflicient to inflame 
the hydrogen, would produce the same eflect. 

Precisely the same phenomena are produced by gal- 
vanism, both in respect to the decomposition of water, and 
the re-union of its elements. When sulphate of copper is 
submitted to the action of a powerful electrical machine, the 
salt is decomposed, and the metal is revived around the 
negative wire. Other metallic salts undergo the same de- 
composition. 

These effects arise from the diflerent electrical states of 
the elements of which the salts are composed, the positive 
element being * attracted to the negative conductor, and the 
contrary. It will be seen directly, that the identity of gal- 
vanism and electricity is proved by many similar results. 

Why is one kind of electricity called vitreous and the other resinous ? 
Which theory is said to be the most simple, and therefore to be preferred ? 
What bodies permit electricity to pass through them without difficulty, and 
what are they called ? What are the best condurtors ? What is the differ- 
ence between conductors and non-conductors ? Why does electricity accu- 
mulate when a non-conductor is excited? When is a body said to be insula- 
ted ? When one side of a body is positive, in what electrical state will the 
other side be ? What are the effects of powerful electrical shocks on water ? 
What are the effects of the same on a mixture of hydrogen and oxygen ? 
Explain Fig. 22, and show how the latter experiment is performed. What 
is it necessary to suppose, in order to explain the decomposition of water by 
electrical agency ? How does electricity act to recompose water from its two 
elements ? What is said in respect to galvanism, as producing the same re- 
sults as electricity ? When sulphate of copper is submitted to the action of 
electricity, what phenomena ensue? How is tiiis effect on the salts ac 
counted for ? 



GALVANISM. 



MAGNATO-ELECTRICITY. 



130. Under electro-magnetism (178) will be found thfi 
description of various magnetic phenomena produced by 
electricity. Mr. Faraday has demonstrated that electrical 
phenomena may also be produced by magnetism, and to 
these are applied the term magnato-electricity. For this 
purpose, let a, figure 23, represent a hollow spiral, or helix of 
copper wire, covered with silk or cotton thread. The ends 
&, c, of this wire are connected with 

a delicate galvanometer (160.) A Fig. 23. 

powerful magnetic bar n. s. is of such 
a size as to be easily introduced into 
the helix. Now, having connected 
the ends of the helix with the galvano- 
meter, introduce the bar, and instantly the magnetic needle 
will be deflected in one direction, and on drawing it out, the 
deflection will be in the opposite direction. Now, as the 
galvanometer can only be moved by the motion of elec- 
tricity in the helix, it is obvious that an electric current is 
produced each time the magnet is placed in it. Hence it 
appears, that if on the one hand electricity produces mag- 
netism, so on the other magnetism produces electricity. By 
causing the pole of a powerful magnet to revolve near a 
coil of copper wire, or the wire to revolve opposite the pole 
of the magnet, an electric current may be established in the 
coil, which may be made sensible by sparks, shocks, and 
chemical effects. 

GALVANISM. 

131. It has already been stated, that the science of gal- 
vanism had its origin from an accidental discovery made by 
a pupil of Galvani, an Italian professor. 

This subject was afterwards prosecuted by Galvani, with 
the most untiring ardor and with great success ; and as his 
discoveries were made known, from time to time, to the 
scientific world, philosophers in all parts of Europe vied with 
each other in repeating his experiments, in varying them in 
all possible ways, and in making new experiments to ac- 
count for the cause of the novel and surprising phenomena 

What is meant by magnato-electricity ? Explain Fig. 22, and describe how 
electric effects may be produced by the magnet. What is said of the interest 
excited among philosophers by the discovery of galvanism ? 



GALVANISM. 63 

they observed. An account of these researches belong to 
the history of Galvanism, and cannot be included in this 
concise epitome of the science. 

132. It must suffice here to state, that the discoveries ot 
Professor Yolta, of Pavia, have contributed more towards 
the progress and development of the true principles of this 
science, than the united researches of all his co-laborers 
The discovery and invention of the Galvanic or Voltak 
pile, the entire merit of which belongs to the Professor of 
Pavia, removed all doubt respecting the identity of elec- 
tricity and galvanism, and is said to have been the result 
of deep m.editation and reasoning. Volta's discovery was 
published in 1800, and since that time several modifications 
and many improvements in the mode of extricating the 
galvanic influence, have been made ; they all, however, 
appear to be founded on his original invention. 

133. To make this subject plain, it is necessary to state, 
that Galvani found, that when the different parts of a re- 
cent animal, as the nerves and muscles, were made to 
touch each other, and then the opposite ends of this series 
made to communicate by means of two different metals, 
signs of electricity were always apparent. Hence Galvani 
concluded that the different parts of animals were in oppo- 
site states of electricity, and that the metals only served to 
restore the equilibrium. On the contrary, Volta maintained 
that the electrical excitement was owing to the contact of 
the two metals, and that the animal substances only served 
to conduct the fluid from the positive to the negative metal. 
And to show that this was the true theory of the phe- 
nomena, he proved by direct experiment, that when a piece 
of zinc and a piece of silver are placed in contact, and 
moistened, they are both excited, the zinc positively and 
the silver negativelj^ Thus, when a piece of silver, as a 
dollar, is placed on the tongue, and a piece of zinc under 
the tongue, and then their two edges made to touch each 
other, electricity will pass from the zinc to the silver, of 
which the person will be sensible, not only by a peculiar 

Wliat philosopher, next to Galvani, has made the most successful re* 
searches on the nature of galvanism? Who discovered the galvanic pile? 
What is said concerning the identity of electricity and galvanism ? From 
what experiment did Galvani conclude that the different parts of animals are 
in different electrical states ? By what simple experiment is it shown that 
when moistened zinc and silver touch each other, electricity passes from one 
to thf other 



64 GALVANISM. 

metallic taste, but by the perception of a slight flash of 
light, particularly if the eyes be closed. 

134. The quantity of electricity evolved by two pieces 
of metal being exceedingly small, Volta tried the experi- 
ment of adding many pieces, an-anging them in pairs, with 
a conductor between them, and found that the galvanic in- 
fluence was increased in proportion to the number of plates 
thus combined. 

Such attempts led him, finally, to construct the Voltaic 
pile already mentioned. This pile consists of a multiplied 
number of galvanic series, terminating at one extremity by 
a positive, and at the other by a negative conductor. 

135. Simple galvanic circle. — The conditions necessar}'' 
for galvanic excitation are entirely different from those un- 
der which common electricity is obtained. We have seen 
that electricity is accumulated when an electric or non- 
conductor is rubbed with the dry hand, or with another 
non-conductor, as a piece of silk, or fur. In ordinary gal- 
vanic excitation, such substances as are called electrics are 
not concerned. 

These, substances are all conductors of the electric fluid ; 
one of them a simple conductor, the other two having each 
the additional power of different degrees of electrical, or 
galvanic excitement. 

These three substances are usually zinc, water, and 
copper, and these, arranged in the order named, compose a 
simple galvainc circle. 

The water, which is mixed with a small quantity of 
acid, not only serves as a conductor of the galvanic fluid, 
from the positive to the negative metal, but also by acting 
slightly on the metals, is the efficient cause of the galvanic 
excitation. 

136. This arrangement, together with the 
course of the electrical agent from one metal 
to the other, and through the water to the 
first metal again, will be understood by Fig. 
24. 

Suppose c to be a plate of copper, and ;s- a 
plate of zinc, touching each other at the top, 
and placed in a vessel of acidulated water. 
Then the action of the acid will produce an 
evolution of electricity from both metals, that 

What is the principle on which the Voltaic pile is constructed^ 




gai-vanis;m. 



b;j 



from the zinc being positive, and that from the copper ne- 
gative. The electrical fluid will therefore pass from the 
zinc, through the water, to the copper, and from the copper^ 
by contact, to the zinc, and so in a perpetual circuit, in the 
direction of the arrows. 

137. Compound galvanic circle. — It is a multiplication of 
this principle ; that is, bj forming a series of simple galvanic 
circles, which composes the galvanic pile, or pile of Volta, 
already mentioned. 

I'his compound galvanic circle is constituted by a series 
of simple circles, so united as to concentrate the influence 
of the whole at a given point. It may be constructed as 
follows : 

Provide three glass rods, say of two feet in length each, 
and fix these in an angular direction from each other in a 
base of wood. Provide, also, circular plates of copper and 
zinc, two or three inches in diameter, about the eighth or 
tenth of an inch thick, and in number proportionate to the 
power of the intended pile Next cut out the same number 
of circular pieces of card paper, or of woolen cloth, that 
there are pieces of either metal, but less in size. Having 
thus obtained the elements of the pile, its construction con- 
sists in placing first on the base, or board, within the rods, 
a plate of copper, then on this a plate of zinc, and next, on 
the zinc, a piece of the paper, or cloth, dipped 
in salt water, or acidulated water, thus form- 
ing a single galvanic circle. The same ar- 
rangement is observed throughout the whole 
series ; that is, copper, zinc, paper ; copper, ™ 

zinc, paper ; except in the last circle, or top 
of the pile, which ends with the zinc. Fig. 25 
represents such a pile, a, 6, being the glass 
rods, and z^ a?, the pieces of wood, the upper 
piece having holes to admit the rods, in order 
to make them secure. 

Such a series affords a constant stream of 
the galvanic influence, but is always most powerful when 
first constructed, or before the plates become oxidated. 




What is the difference between the substances used to collect electricity, 
and galvanism? What three substances usually compose a simple galvanic 
circle ? What is the use of the water and acid employed in the extrication 
of galvanism? Explain Fig. 24, and show the course of the galvanic fluid ? 
How is the pile of Volta constructed ? After the frame is made, and the 
plates of metal and paper prepared, how is the pile then constructed ? When 
.ioe-s the pile operate most powerfully ? 



66 GALVANISM. 

(.>ii this account, after ha\ang been some time in use, it 
requires to be taken in pieces, the plates cleaned from rust, 
and then again reconstructed, when it regains its oiiginal 
energy. 

138. A pile composed of two dozen plates of each metal, 
will give a small shock, which, when taken bj the hands, 
may be felt to the elbows. The mode of receiving the 
shock is by wetting the hands, and then having placed one 
of them in contact with the zinc plate, which terminates 
one end of the pile, touch with the other hand, the copper 
plate which terminates the other end of the pile. Or, these 
two plates may be touched with a wire, wound with a wet 
rag, and held in the palm of each hand. When experi- 
ments are to be made by passing the galvanic influence 
through any substance, this is done by connecting a wire 
with each terminating plate ; the two movable ends of the 
wire being then brought near each other, and the substance 
placed between them, the fluid passes from the positive to 
the negative side, and so through the substance. These 
wires are called the poles of the Voltaic pile. 

139. Any number of these piles may be connected together 
by making a metallic communication from the last plate of 
the one, to the first plate of the other, always observing to 
preserve the order of succession from the zinc to the copper, 
and from the copper to the zinc. In this manner a galvanic 
battery is constructed, the power of which will be propor- 
tionate to the number of plates employed. 

140. The galvanic fluid, it ought to have been observed, 
is extricated only on condition that one of the metals em- 
ployed be more easily oxidated, or more readily dissolved in 
an acid, than the other. Any two metals will form an 
effective galvanic apparatus on this condition, and it is al- 
ways found that the metal having the strongest affinity for 
oxygen is positive, while the other is negative. Thus, any 
metal, except that which has the least affinity for oxygen 
of all, may lorm the positive or negative side, by having 
another metal, more or less oxidable than itself, placed in 
contact with it. 

How may the pile, after the plates have become oxidated, be made as pow- 
erful as at fii-st ? What is the mode of receiving the shock from the galvanic 
pile ? When it is required to pass the electricity through a substance, how 
is this done? What are the wires, or conductors, called? How is a gal- 
vanic battery constructed? How must the metals differ, in respect to their 
affinity for oxygen, in order to evolve galvanism ? In what electrical state if 
the metal which has the strongest affinity for oxygen ? 



GALVANISM. 



67 



141. Copper, in contact with zinc, is negative, becduse 
zinc is most easily dissolved, or has the strongest affinity 
for oxygen of the two. But when copper is in contact with 
silver, it becomes positive, while the silver is negative; and, 
for the same reason, silver becomes positive when in contact 
with gold, or platina. The greatest effect is produced, other 
circumstances being equal, when two metals are placed to- 
gether, one having the greatest, and the other the least 
affinity for oxygen, as zinc and platina. 

142. Since the invention of Volta, a great variety of dif- 
ferent methods have been devised, in order to extricate the 
galvanic fluid with greater convenience, or with greater 
power, and also to modify its action for different purposes. 

143. Zinc and copper cups. — But perhaps the most simple 
and convenient method of using small degrees of the gal- 
vanic power, is by means of cylindrical cups, composed of 
copper and zinc. By this arrangement, the exciting acid 
is contained within the cup of copper, while the zinc may 
be taken out and cleaned with httle trouble ; and besides, 
the apparatus may be constructed by almost any one who 
possesses a small sheet of copper, and another of zinc. 

144. This arrangement will 
be understood by Fig. 26, 
where c is a double cup, made 
of two cylinders of sheet cop- 
per, of unequal size, placed 
one within the other, and sol- 
dered to the bottom, leaving 
the space of an inch between 
them, for containing the acid 
solution. The cup z, is of 
zinc, and is inserted between 
the copper cylinders, but is kept from contact with them by 
small pieces of cork, or wood. This is not fixed, by solder- 
ing, but may be removed at pleasure for cleaning, the gal- 
vanic power being most intense when this is free from oxide. 
The small cups, a, a, are very useful appendages, for by 
filling them with mercury, and inserting the ends of the 
conducting wire, the voltaic circuit may be continued, or 




What will be the state of copper when in contact with zinc ? What will 
be the state of copper when in contact with silver or gold? What metals 
will produce the greatest efFect on this account ? Describe the small bat- 
tery, made of zinc and copper cylinders ? What are the uses of the httle 
cups, a, a, in the figure ? 






H8 GALVANISM. 

brokf'ii at pleasure. These may be made of percussion caps, 
soltlered on the ends of brass, or copper wire. 

145. The exciting solution for these cups may be made 
of a solution of sulphate of copper, in water, or of dilute 
sulphuric acid, to which is added a httle common salt. 

146. Cup battery. — Another mode of arranging the gal- 
vanic apparatus, is by means of a row of glasses, each con- 
taining solution of common salt, or a dilute acid. In each 
glass is placed a plate of copper, and another of zinc, not in 
contact, but so connected by slips of metal, or by wires, that 
the zinc in one cup shall be connected with the copper of 
the next cup ; the zinc in the second cup with the copper 
of the third, and the copper of the third with the zinc of the 
fourth, and so on through the series, except the terminating 
cups, which contain only a single plate each, one of copper, 
and the other of zinc. This arrange- 
ment will be understood by Fig. 27, 
where «, a, «, are the glasses, z. the 
zinc, j:, the copper, and r/;, the wires 
by which they are connected. The 
advantage of this method consists in 
the exposure of the two sides of the 
plates to the action of the acid ; while, 
by soldering the plates, as in the construction of the gal- 
vanic trough, one of the surfaces of each metal is protected 
from the acid, and contributes nothing to the effect. But 
the bulk of this apparatus, and the danger of breaking the 
glasses, in case of transportation, prevents its general 
adoption. 

147. Trough battery. — A convenient, and more compen- 
dious modification of this principle has therefore been con- 
trived, and is called the trough battery. In this arrange- 
•nent, the zinc and copper plates are united in pairs, as just 
eiescribed, by means of slips of metal, which are soldered 
to each other. Twelve pairs of these plates are then fas- 
tened to a piece of baked wood, being placed at such a di »- 
tance apart, as to fit the cells of a trough, which contains 
»he water and acid. The trough may be made of baked 
iiicihogany, with partitions of glass ; or, what is better, the 
whole may be made of earthen, or Wedgewood's ware. 

Describe the mode of extricating galvanism by means of glass cups ? 
Why is the apparatus made with cups objectionable ? In what is called the 
trough battery, how are the plates united ? 




GALVANOMETER. 69 

148. When this battery is to be used, the cells in the 
troiig:h are partly tilled with water, containing an acid, or 
salt in solution, and then the plates, being connected with the 
slip of wood, are all let down into the cells at the same in- 
stant, by means of a puUej', each cell containing one plate 
of zinc and another of copper. 

149. Where great power is wanted, any number of these 
troughs may be connected together, by passing a slip of 
copper from the positive end of one, to the negative end of 
the other trough. For the use of a laboratory, this is by far 
the most convenient, as well as the most powerful means of 
obtaining a large quantity of the galvanic fluid yet de- 
\qsed. When an experiment is finished, the operator, in a 
few minutes, can raise all the plates from their troughs hy 
means of pullies, and thus they are suspended, ready to be 
let down again when wanted. The power also, with the 
same extent of surface, is double that of the galvanic trough, 
where the plates are soldered together, since with the pre- 
sent method, the entire surface of each metal is exposed to the 
action of the acid. The plates can likewise be more readily 
cleaned, and the whole apparatus more easily kept in repair. 

The Galvanic Battery of the Royal Institution of Great 
Britain, is constructed on the above plan. It is of immense 
power, consisting of 200 troughs of Wedgewood's ware, 
each containing ten cells, and receiving ten double plates of 
copper and zinc, each plate containing a surface of 32 square 
inches. The whole number of double plates is therefore 
2000, and the whole metallic surface exposed to electrical ex- 
citation at the same instant, is equal to 128,000 square inches. 

It was by means of this apparatus that Sir Humphrey 
Davy performed his brilliant experiments, and succeeded in 
decomposing the alkalies, and showing their metallic bases. 
{See Potash and Soda.) 

GALVANOMETER,. 

150. This is an instrument for ascertaining the presence 
of a current of electricity, or galvanism, by the deviation 
which it occasions in the magnetic needle. The simplest 

In the trough battery, how are the plates of metal brought into contact with 
the acid ? What are said to be the advantages of this method ' Why is 
this battery more powerful than the galvanic trough in which the plates are 
soldered together? What peculiar conveniences has this arrangement? 
What number of double plates does the battery of the Royal Institution con- 
sist of? What important discoveries did Sir H. Davy make by means of 
this battery ? What is the galvanometer ? 




70 CHEMICAL EFFECTS OF GALVANISM. 

galvanometer is a magnetic needle suspended between 
two parallel copper wires, connected with the galvanic bat- 
tery. The wires should be insulated by covering them 
with silk, or cotton thread, and then var- 
nished. The cups, a b, Fig. 28, at the Fig. 28. 
ends of the wires, are filled with mer- a 5 
curj for the convenient insertion of the 
two poles, coming from the source oi 
electricity, or galvanism. When this 
needle is placed parallel to the coil, and 
in the magnetic meridian, as represented 
in the figure, it instantly deviates when the electrical cur- 
rent passes through the wires, and the deviation is eithei 
to the east or west, according to the direction of the cur- 
rent. If several coils of the wire be passed around the 
needle, the two ends being left free, as in the figure, the 
effect on the needle will thereby be increased. 

CHEMICAL EFFECTS OF GALVANISM. 

151. It is a singular, and, perhaps, unaccountable fact, 
that the extent of the continuous surface of the metals, 
from which the galvanic fluid is obtained, has an influence 
over its effects, when employed for various purposes. We 
should suppose, both from reasoning and analogy, that the 
amount of galvanic action would, in every case, be propor- 
tioned to the number of square inches of metallic surface, 
and that it would make no difference in the result, whether 
the individual pieces of metal were large or small. But 
experience shows that this is not the case. The effect of a 
battery composed of large plates, and one of small plates of 
the same extent of surface, is quite different. That com- 
posed of the large plates having the most intense chemical, 
or heating power, while that consisting of small ones 
has the greatest effect on the animal system. Thus, a man 
can bear with little inconvenience the shock from Mr. Chil- 
dren's battery, composed of plates six feet long, and two feet 
and a half wide ; while he would be stunned, or perhaps 
killed, by the shock of the same amount of surface, were it 
divided so as to proceed from plates of only two or three 
inches in diameter. And yet Mr. Children's battery gives 

What is the construction of this instrument ? How is it employed ? Is there 
any difference in the effect of a battery composed of large or small plates, 
when the extent of their surfaces is the same ? What is the diflFerence be 
tween the effects of large and small plates ? 



CHEMICAL EFFECTS OF GALVANISM. 71 

the most intensely brilliant calorific effects, while the calorific 

agency of the small plates is comparatively slight and in- j 

significant. . . | 

152. The decomposing chemical effects of galvanism 4 
have been much more extensively employed than those of j 
common electricity. Indeed, the decomposing power of * 
electricity was httle known before the brilHant discoveries 

of Sir H. Davy, by means of galvanism ; but since that 
time, Dr. Wollaston has shown that most, if not all the 
chemical effects of the galvanic battery, may be produced ^ 

by electricity. ^ , 1 1 

153. The decomposition of water, by means of electricity 
was effected by the Dutch chemists long before the discovery 
of galvanism. A description of the method of doing 
this has already been given, while treating of electricity: 
This seems to have been the most important chemical de- 
composition effected by electricity, before the discoveries of 
Galvani and Volta. v 

Since that period, the science of chemistry has owed to , 

that of galvanism some of the most magnificent and impor- 
tant discoveries ever made in that science, viz., the decom- 
position of the alkalies, and, as a consequence of this, other 
discoveries of great interest and value. 

154. One of the most extraordinary facts belonging to the 
agency of galvanism, is the discovery that the elements of 
decomposed bodies follow an invariable law in respect to the 
electrical sides on which they arrange themselves. Thus, in 
decomposing water, or other compounds containing its ele- 
ments, the hydrogen escapes at the negative pole, and the 
oxygen at the positive. In the decomposition of the salts 
(see Salts) and other compounds, this law is in every in- 
stance observed, the same kind of element being always 
disengaged at the same pole of the battery. 

When a compound consists of two gaseous elements, they 
may be readily separated, and each gas obtained separate, 
by placing the compound in a bent tube, and then exposing 
it to the galvanic action. 

This simple arrangement is represented by Fig. 29. 

Will electricity produce the same chemical effects as galvanism ? Was the 
decomposition of water effected by electricity before the discovery of gal 
vanism ? Of what use has galvanism been to chemistry ? In the decom- 
position of water by galvanism, at which pole of the battery does hydro- 
gen ■nlways escape "^ 




72 CHEMICAL EFFECTS OF GALVANISM. 

It consists of a glass tube, bent as 
in tlie figure, a small orifice being 
ground at the angle so as to let in the 
water; or instead of this, two tubes 
may be used with their lower ends 
placed in contact. The tubes being 
filled with water, and their lower ends 
placed in a dish of the same fluid, the 
two platina wires proceeding from the 
tw-o sides of the battery are passed 
through corks in the upper ends of the 
tubes, and pushed down, so as to come within about the 
eighth of an inch of each other. Care must be taken that the 
adjustment be such as to allow the gases as they ascend to 
come within the orifices of the tubes. 

155. The battery being now set in action, small bubbles 
of gas will be seen to arise from the ends of the wires, but 
in different quantities. The tube from the negative wire 
will soon be filled with hydrogen gas, while the other in 
the same time will be only half filled with oxygen. This 
circumstance arises from the fact, that in forming water, 
these two gases combine in the proportion of two volumes 
of hydrogen to one of oxygen. Of course, therefore, w^hen 
water is decomposed, the volume of oxygen is only half 
that of hydrogen. 

In this experiment, the poles of the battery must be of 
platina, or gold, otherwise, if they are made of iron, or other 
oxidable metal, the oxygen combines with the metal instead 
of being extricated and rising up the tube. 

When neutral salts, whether alkaline, metallic, or earthy, 
such as common salt, bh.ie vitriol, or alum, are exposed to 
the action of a powerful battery, the same law is observed ; 
the acid, which contains the oxygen, goes to the positive 
wire, while the bases, being alkalies, metals, or earths, are 
transferred with the hydrogen (for these salts always con- 
tain water) to the negative wire. 

156. But the most surprising effects of the power of this 
principle is exhibited when the compound is placed in cups 
connected with the two sides of the battery, and the two 

Describe the method of decomposing water by galvanism, and of retaining 
the two gases in a separate state. In performing this experiment, why is the 
rube on the negative side first filled with gas? In decomposing the salts, 
what law is observed in respect to the poles at which their elements are 
extricated. 




CHEMICAJ. EFFECTS OF GALVANISM. 73 

constituents of the compound are transferred from one cun 10 
the other. ' 

Jf the solution of any sahne compound, such as Glaubers 
sah, be made m water, and phiced in two cups, one con- 
nected wuh the positive, and the other with the ne-ative side 
of the battery, then, by making a communication between 
the cups, by means of some moistened asbestos, or cotton 
and setting the battery in action, the two constituents of the 
salt will be transferred from one cup to the other 

157. Fig. 30 will show the sit- 
uation of the cups, the asbestos, ficr 30 
and the galvanic poles of this ^ ' 
experiment. Both cups con- 
tain a solution of Glauber's 
salt. This saJt is composed 
of sulphuric acid, soda, and 
water. The cup P is connec- 
ted to the positive side of the 
battery, by a wire, passing into the fluid, and the cup N 
with the negative side, m the same manner. The cups are 
connected by the moistened asbestos passing from the fluid 
of one to that of the other. When this arrangement is 
Completed, and the battery has been some time in action 
It will be found that the water in the positive cup will have 
an acid taste, while that in the negative cup will ha e an 
alkaline taste ; and if the action be continued a suffi ient 
time, ail the acid contained in the salt will be found in ^ne 
cup, and all the soda in the other. 

158. Nor does it appear to make any diflbrence in the 
resuh, at what part of the fluid circuit the salt to be decom- 
posed IS placed. 

This is proved by 
placing three cups 
in a hne, and con- 
necting them to- 
.ii:ether by moistened 
asbestos, as shown 
by Fig. 31. If the 
Glauber's salt, or 

Explain Fig. 29 and describe how the elements of the salt are transferred 
rom one cup to the other. In which cup is the acid, and in wh ch is he 
alkah found? Describe Fig. 30, and show into which cup the s^lt is nlaVed 
and into which its different elements are transferred by the ealvan ■ actioa 
cabbte /^' '^''^''°' "' ^^""^ '^' ^"^ °"^^i^« '^^^ with'tnfusbn of red 



Fig. 31. 




74 GALVANISM. 

any other saline compound be put into the middle cup, and 
waUT nito the others, and the two galvanic poles be con 
nected with the other cups, P being the positive, and N the 
negative side, then all the acid will be transferred to the 
positive, and all the alkah to the negative cup, while the 
water in the middle cup will remain nearly in a state of 
purity. If the two outer cups be filled with an infusion of 
red cabbage, instead of simple water, the operator can see 
the progress of his experiment, since the contents of one cup 
will be turned red by the acid, and the contents of the other 
green by the alkali. 

159. A phenomenon of a still more extraordinary kind 
occurred to Sir H. Davy, during his experiments on this 
subject. For it was proved that the galvanic action was 
capable of suspending the laws of affinit}^, so that an acid 
might be conveyed through an alkaline substance, or an 
alkali through an acid, without any combination taking 
place between them, or either might be passed through a 
cup of infusion of cabbage, without changing its color. The 
three cupi. being arranged as in the last experiment, and 
connected together by films of moistened cotton, or asbestos, 
there was put into the negative cup, N, a solution of sul- 
phate of soda, and into the other two cups, an infusion of 
red cabbage in water; this infusion being one of the mo.^^t 
delicate tests of the presence of an acid or an alkali. After 
these cups, so arranged, had been for a short time placed in 
the galvanic circuit, the infusion in the positive cup became 
red, and afterwards strongly acid, while that in the middle 
cup continued of the same color as at first. Thus, as the 
salt was decomposed, its acid passed through the middle 
cup without mixing in the least with the water it contained, 
otherwise its color would have been changed. On reversing 
the connections with the poles of the battery, the alkali of 
the salt was transferred to the opposite cup, the solution of 
which it tinged green, without in the least affecting the 
color of that in the middle cup. 

On placing an alkaline solution in the middle cup, the 
acid was transferred through it without combination ; and 



What extraordinaiy phenomenon is observed in respect to the suspension 
of the laws of affinity by galvanic action ? Describe the exppriment by which 
it was found that an acid or an alkali was made to pass through a cup of infu- 
sion of '"abbage without changing its color. What are the other proofs show- 
ing that galvanic action suspends the action of affinity ? How does Sir H 
Davy account for these phenomena t 



GALVANISM. 75 

when an acid was placed in that cup, an alkali passed 
through it in like manner. 

160. Theory of Galvanism. — To account for the phe- 
nomena of galvanism, Sir Humphrey Davy supposed that 
the eleraenis of compound bodies were in different and oppo- 
site spates of electricity, but that during their chemical 
union, an equilibrium existed in these electrical states. This 
theory we have already mentioned, in accounting for the 
decomposition of water by common electricity. But Sir H. 
Davy beheved it to extend in general to all chemical com- 
pounds. To explain how the elements of bodies may be in 
this state, he supposed that each element is naturally pos- 
sessed with a portion of electricity, whether it is in a state 
of combination or not ; and that the elements, in this respect, 
naturally divide themselves into two classes, one of whicli 
is endowed with positive, and the other with negative elec- 

^tricity. In proof of this, it is found as an experimental fact, 
that oxygen, chlorine, iodine, (see the latter article.,) and 
acids in general, are naturally negative, while hydrogen, 
the metals, and the metalnc oxides, and the alkalies, are 
naturally positive. Thus it appears that bodies having the 
strongest attraction or chemical affinity for each other, are 
naturally in opposite states of electricity, and that the sup- 
porters of combustion, oxygen, chlorine, and iodine, are all 
negatively electrified. 

161. From such considerations, Sir H. Davy not only 
accounts for the chemical agency of the galvanic fluid, but 
also for that force called affinity, or chemical attraction, 
which impels bodies of different kinds to unite and form com- 
pounds. Thus, oxygen being naturally negative, and 
hydrogen naturally positive, they unite with a force or 
energy proportional to the difference of their electrical 
states. 

162. The decomposing force of the galvanic battery may 
readily be accounted for on the same principle ; for if water 
be presented to any substance of a higher state of positive 
electricity than its hydrogen, then a decomposition would 

In what state of electricity are oxygen, chlorine, iodine, and the acids gene- 
rally ? In what state are hydrogen and the metals? Are bodies having the 
strongest chemical affinity for each other, in the same or in opposite states 
of electricity ? How is the decomposing force of galvanism accounted for? 
What is said in relation to the truth, or probability, of the electrical theory 
advanced by Sir H. Davy? 



76 GAI//AMSM. 

o.Tisue, because the oxygen would leave the hj'-drogen, and 
ai.fich itself to that substance for which it had the strongest 
attraction. The voltaic battery produces this effect, by 
ol!'ering to the two constituents of water stronger opposite 
electrical energies than these two substances have for each 
other. Thus, supposing the electrical force of hydrogen for 
oxygen to be equal to 3, and that of oxygen to hydrogen to 
be equal to 3, then they would combine with a force equal 
to 6. But if we suppose the galvanic battery to offer to the 
oxygen a positive electrical energy equal to 4, and at the 
same time to the hydrogen a negative energy equal to 4, 
then it is obvious that their combining force would be over- 
come, and that the oxygen would fiy to the positive, and the 
hydrogen to the negative poles of the battery, and thus that 
compound w^ould be reduced to its original elements ; and 
we find that this is exactly what happens as a fact, when 
the water is exposed to the galvanic circle. 

163. This, it must be acknowledged, is one of the most 
beautiful theories ever invented, and at the same time agrees 
with the phenomena observed in most energetic chemical 
changes. But there are still some facts for which it does 
not satisfactorily account ; nor is it absolutely certain, that 
in any case, chemical attraction is owing to the different 
electrical states of the combining bodies, so that in the pre- 
sent state of knowledge, this theory must be taken only as 
a probable and highly ingenious hypothesis. 

164. Heating effects of Galvanism. — One of the effects of 
galvanic action is the evolution of heat; and where the action 
is strong, it is accompanied with light, but not otherwise. 

There is a remarkable difference between the conditions 
necessarj^ to the evolution of heat by galvanic action, and by 
common electricity. In common electricity, there is no pro- 
duction of heat, where the fluid moves through a perfect 
conductor, and without obstruction. When it moves along 
a rod of metal, no sensible heat, or light, is evolved, unless 
the conductor is too small for the quantity. But in its 
passage through non-conducting substances, as au', or dry 
wood, both heat and light are a consequence. 

But when galvanism passes through a perfect conductor, 

Is it certain that in any case chemical attraction is caused by opposite elec- 
trical states ? What is said of the heating effects of galvanism? What are 
the different conditions under which heat and light is evolved by electricity 
and galvanism ? When galvanism is passed through a perfect conductor, 
what effect is produced ? What is the effect when it is passed through water ? 



GALVANISM. 77 

and tlie circuit remains entire, and when nolig?it is evolved, 
there is still an elevation of temperature caused by its 
passage. 

This is readily proved by making the two poles of tne 
battery meet in a vessel of water containing a thermometer, 
when it will be found that the temperature of the water will 
soon be raised, and if the experiment be continued, the fluid 
will boil by the heat evolved. 

165. If the battery consists of an extensive series of elec- 
trical circuits, very powerful calorific effects are produced by 
the passage of the fluid through metallic wires. Iron wire 
is melted and falls down in globules, and steel wire burns, 
with corruscations too brilhant for the unprotected eye. 

The heating effects of galvanism seem to depend oil the 
conducting power of the metal employed, the heat being in 
an inverse ratio to the power of the conductor. This is 
curiously illustrated by passing the fluid through a wire, or 
chain, composed of alternate portions, or links, of platina 
and silver, soldered together, when it will be found that the 
silver will scarcely be warmed, while the platina will be 
intensely ignited. 

166. It appears from some experiments made with Mr. 
Children's great battery, that the heat excited by voltaic 
action is more intense than that produced by any other 
means. Many substances were fused by it, which were 
exposed to the best wind furnaces, without any impression. 
A piece of platina wire, one thirtieth of an inch in diameter, 
and eighteen inches long, became instantly red, then white 
hot, with a brilhancy insupportable to the eyes, and in a 
few seconds was fused into globules. Still, this battery had 
little eflfect on water, or on the human frame, the shock 
being felt no higher tlian the elbows. 

167. But still more brilliant effects were produced by the 
battery of the Royal Institution, when pieces of charcoal 
were attached to its poles, and then brought near each 
other. 

This battery, when the cells were filled with a mixture 
of sixty parts of water, and one part of nitric, and one of 
suli)huric acid, afforded the most splendid and impressive 

How are metallic wires affected by powerful galvanic action ? When gaK 
vanism is passed through a chain, the links of which are alfernataly silver and 
platina, what is the effect on each metal ? What is said of the power of Mr. 
Children's battery ? What effect does this battery have on the human frame * 




78 MAGNETISM. 

results. When pieces of charcoal, about one inch long, and 
the sixth of an inch in diameter, were placed in the circuit, 
and made to approach each other, a bright spark was seen 
to issue from one to the other, and, in a moment, the char- 
coal became ignited to whiteness. Then, hy widening the 
space between the charcoal points, a constant discharge 
continued, when they were four inches apart, affording a 
most brilliant ascending arch of light, broad in the middle, 
and terminating in points 

at the charcoal, resem- Fig. 32. 

bling, in shape, two cones, ^ , -^,^i~ 

apphed base to base. The ^ 
shape of this brilhant phe- 
nomejion is represented at 
Fig. 32, where «, and Z>, 
are the poles of the battery, with pieces of charcoal attached 
to them, and, between these, the ascending arch of hght. 
When any substance was held in this arch, it became in- 
stantly ignited ; platina, one of the most infusible of all the 
metals, melted in it as readily as wax in a candle ; quartz, 
sapphire, magnesia, and hme, all entered into fusion; and 
points of diamond and plumbago rapidly disappeared, seem- 
ing to evaporate with 'the heat. 

ELECTRO -MAGNETISM. 

168. It is perhaps a singular fact, that notwithstanding 
the very numerous and philosophical experiments made on 
the subject of Electricity, that no one, until at a compari- 
tively recent period, ever noticed any connection between 
that power and magnetism. And yet electricity is never set 
in motion, unless magnetism is at the same time developed. 
This was first observed by Prof Oersted, of Copenhagen, 
and has since become the source of an important series of 
discoveries, both to science and the arts. 

169. If a suspended magnetic needle be brought near a 
wire through which an electric current is passing, the 
needle will immediately deviate from its usual position, and 
assume a nev/ one, depending upon the relative position of 
the needle and wire. On placing the electric wire above .^ and 

"N^'Tiat are the effects when pieces of charcoal are placed near each other, 
in a powerful galvanic '-.xrcnit ? Describe Fig. 31. What substances were 
fijsed by the bauery of the Royal Institution/ What is the fourth impondera- 
ble agent belonging to our list? What is said of magnetism in connection 
with electricity ? Wliat takes place when a magnet is brought near an elec 
trical current? 



MAGNETISM. 79 

parallel to the magnet, the pole next to the negative end of 
the battery ahvaj's moves towards the west ; and when the 
wire is placed IdcIow, or under the needle, the pole turns 
towards the east. When the electric wire is on the same 
horizontal plane with the needle, no declination takes place; 
but the magnet shows a disposition to move in a vertical 
direction, the pole next the negative side of the battery being 
depressed when the wire is to the west of it, and elevated 
when it is at the east. 

170. The magnetic phenomena of a wire transmitting 
electricity are such as to appear dependant upon the cir- 
culation of the magnetism at right angles to the electric 
current, so that if n p. Fig. 33, repre- 
sent the negative and positive poles of Fig. 33. 

the wire, transmitting a current of ^ 

electricity in the direction of the hori- jjP 
zontal darts, a current of mag'netism ■- 
will be established in the direction of 

the vertical dart, n s, appearing to move round the axis of the 
electrical current ; hence the name vertiginous^ or rotary mag- 
netism, sometimes apphed to these phenomena. That such a 
rotary current exists under the conditions above described, is 
proved by the fact that, if a magnet has one of its poles loosely 
fastened, and the other free, the electric influence will give 
the free pole a circular motion ; while under the same cir- 
cumstances, the electric wire will rotate around the magnet. 

171. If a steel needle be placed in contact with the elec- 
tric wire, and parallel to it, the needle wiU acquire opp3site 
magnetic poles upon its sides ; but if it is placed at right 
angles to the wire, it will become polar, and possess all the 
properties of a permanent magnet, but shght in degree. 

172. If a piece of copper wire be coiled by winding it 
around a solid, say half an inch, or less, in diameter, the 
folds not touching each other, an elec- 
trical helix will be formed, as represented Fig. 34. 

by Fig. 34. This being connected with 
the two poles of an electrical battery, and 
a steel needle placed for a second within 
its folds, the needle will be found a strong, 
permanent magnet, and may be em- 



When the electrical wire is above the maoinet, which way does it turn? 
'V^hen below, which way does it move ? In what manner does the magnetism 
move with respect to the electrical current? How is it proved that an elec 
trical rotary current exists? How is the ele©trical helix formed ' 




8(? ATTRACTIOJS. 

ployed for any purpose for which magnetic polarity is re- 
quired. Hence we must conclude that the force of the 
magnet depends on the repetition of the electrical influence, 
since, as stated above, if the needle be merely crossed by a 
single wire, a weak magnet only is produced. 

For these, and many other experiments, the little battery 
already described, consisting of cylinders of copper and zinc, 
is sufficient. 

ATTRACTION. 

173. By attraction is meant that property in bodies which 
gives them a tendency to approach each other, whether 
they exist in atoms, or masses. Attraction has received 
various names, according to the circumstances under which 
it is obsen'ed to act. Thus, that kind of attraction which 
extends to all kinds and quantities of matter, and to all dis- 
tances, is called attraction of gravitation. This attraction 
extends reciprocally from one planet to another, and from 
all the planets to the fixed stars, and is the cause of the 
orbicular motion of the heavenly orbs. It also extends to 
all terrestrial masses of matter, and is the cause of their 
weight, or tendency to approach the centre of the earth. 

174. The force of gravitation is directly as the quantity 
of matter, and inversely as the square of the distance. The 
quantity of matter being given, and the attracting force at a 
certain distance, say four feet, being known, then this force 
will increase, or diminish, as the square of the distance. 
Thus, if one body attracts another, at the distance of two 
feet, with a force of 36 pounds, then, at the distance of four 
feet, its force of attraction will be only \ as much, or 9 lbs., 
and so in this ratio, whatever the distance may be. (See 
Natural Philosophy.) 

175. By attraction of cohesion, or aggregation, is meant 
that force which tends to preserve bodies in masses, by acting 
on the particles of which they are composed. This attrac- 
tion is supposed to act only at insensible distances, as when 
the atoms of bodies touch each other, and only when the 
particles of matter are of the same kind. 



What is '^he use of the electrical helix? How is it shown that the mag- 
netic ffo-c" depends on the repetit)on of the electrical influence ? What 
mount by attraction ? What is attraction of gravitation ? What are the laws 
of attractive force? Suppose a body is attracted with a force of 36 pounds, 
at the distance of two feet, what will the force be at the distance of four feet? 
What is meant by attraction of coh^'sw '' 



AFFINITY. 81 

176. Chemical Attraction is that power which forces the 
particles of bodies of different kinds to combine and form a 
compound. This force is also called ajffinity^ because this 
kind of union takes place only between particular sub- 
stances. Like the attraction of cohesion, it acts only at in- 
sensible distances ; that is, the particles of bodies must be 
brought into the immediate vicinity of each other before they 
will combine. But it differs from cohesive attraction in 
taking place only between heterogeneous atoms, or among 
particles of different kinds of matter. Several other kinds 
of attraction are described, [See Natural Philosophy^) but it 
is chemical attraction, or affinity, which must more imme- 
diately occupy our attention here. 

AFFINITY. 

177. Chemical attraction is a subject of the highest im- 
portance in the study of chemistry, since a knowledge of 
the whole science includes little more than an acquaintance 
with the laws and effects of affinity, that is, of chemical 
attraction and repulsion. 

We have already noticed that this science is founded on 
experiment, and from deductions arising from facts thus 
discovered. Now, chemical experiments are only the 
means of discovering chemical affinities, and a knowledge 
of these affinities are the facts on which the whole science 
is founded. 

178. By experiment we know that some bodies have an 
affinity to each other ; that is, we know that on presenting 
them to each other, under certain circumstances, they will 
combine, and form a third substance, which differs from 
either of the first. We know, also, by the same means, 
that other substances, when presented together in the same 
manner, will repel each other ; that is, they will not com- 
bine, nor can they be made to unite, so as to form a third 
substance. 

This kind of knowledge it is impossible for man to ac- 
quire without actual experiment ; for by no process of rea- 
sonmg could he ever determine before-hand, whether two 



What is chemical attraction? How do cohesive and chemical attractions 
diifer? In what respect is a knowledge of chemical attraction important? 
In what does a knowledge of the science of chemistry chiefly consist ? 
What are the facts on which the science of chemistry is founded ? How is it 
known that some bodies attract, while others repel each other ? Is it pes 
sible %o gain any knowledge of ctiemistry, except by experiment ? 

4* 



82 AFFINITY. 

bodies would attract or repel each other, any more than he 
could tell what they were composed of by mere inspection. 

179. We know, for instance, that when we mix acid 
and water, the two liquids unite, or blend together ; now 
by reasoning from analogy, we should have the same 
grounds for believing that any other fluid would unite with 
water, that we had for believing that an acid would, and 
therefore that oil and water would combine, as well as acid 
and water. But experiment shows, that on this subject, 
neither reason nor analogy lends us the least aid, for, on 
mixing the oil and water, we find that they mutually repel 
each other, and though blended together by force, they 
again separate as soon as the force is removed. 

180. It is, then, only by actual experiment that we can 
decide whether two bodies have an affinity for each other, 
and consequently, whether they are capable of forming a 
chemical compound, or not. 

181. There are several circumstances which affect the 
results of chemical affinity, or conditions on which its 
action depends, which will be mentioned in their turn. 
There are, also, several kinds of affinity, which have re- 
ceived different names, depending on the conditions under 
which its action takes place. These appellations and con- 
ditions will also claim attention as they occur. 

182. With a few exceptions, the first condition necessary 
to effect chemical combination is, that one or both the 
bodies should be in a fluid state ; since, however strong the 
affinity of two bodies may be to each other, their particles 
cannot unite unless they are free to move. Hence, to effect 
the combination of solids, their cohesion must first be de- 
stroyed, either by solution in a fluid, or by means of heat. 
The acids and alkahes have a strong affinity for each 
other, but on mixing them, even when in the finest powder, 
no chemical combination ensues, because, in all chemical 
compounds the union takes place between the atoms of the 
combining substances. 

But on pouring a quantity of water upon such a mixture, 
chemical action instantly ensues, and a third substance, 
differing entirely from the alkali or the acid, is the result of 
the combination. This compound is called a salt. 



What reason would there be to suppose, without experiment, that oil and 
water would not combine ? What is the first condition necessary to effect 
chemical union? What is necessary, in order to effect the chemical com- 
bination of solids ■? Why will not solids combine as well as fluids ? 



S i:\GLE ELECTIVE AFFINITl. S3 

In like manner, if zinc and copper be reduced to the 

finest powder, and mixed ever so intimately by mechanical 
force, lliere will still be no intimate union between their par- 
ticles. But if heat be applied so as to reduce them to a 
fluid state, they combine with considerable energy, and 
torm a yellow alloy, called brass, which differs greatly from 
the zmc or copper of which it is formed. 

SIMPLE AFFINITY. 

183. The most simple cases of affinity are afforded by the 
mixture of two substances which have the power of com- 
bining with each other, in any proportion. Water and 
sulphuric acid, or water and alcohol, form such combi- 
nations. What are termed neutral salts, which are formed 
by the union of a pure acid, and a pure alkali, are instances 
of the same kind, only that they do not combine in all pro- 
portions. In a great variety of instances, after two sub- 
stances have combined, when mixed alone, or without the 
admixture of any other substance, this first union may be 
destroyed by the intervention of another, or a third sub- 
stance, having a stronger attraction for one of these sub- 
stances than they have for each other. This forms an 
instance of what has been termed by Bergman, Elective 
Affinity. 

SINGLE ELECTIVE AFFINITY. 

184. This is exercised when one composition is destroyed, 
and at the same time another is formed. There are many 
familiar examples of this kind of decomposition, some of 
which we witness almost every day. Camphor dissolved 
in alcohol, or in strong spirits, makes a transparent solution; 
but if water be poured into this solution, it instantly be- 
comes turbid, and the camphor separates from its con- 
nection with the alcohol, and rises to the surface of the 
fluid. This separation takes place because the alcohol 
has a stronger affinity for the water than for the camphor, 
and the turbidness is caused by the insolubility of the 
camphor in water, in consequence of which it takes the 
solid form. 

Soap is composed of oil, an alkali, and water. The oil 



In what manner may ropper and zinc be made to combine? What are 
the most simple cases of affinity? Give an illustration of this affiD>ty 
What is single elective affinity ? 



84 SINGLE p:lective affinity. 

ant I water have no affinity for each other, but the alkah 
has a strong- affinity both for the oil and water, and con- 
sequently the three substances unite and form a compoun'L 
But if an acid be mixed with a solution of soap, the com 
pound is decomposed, for the alkali has a stronger attrac 
tion for the acid than for the oil and water, and consequently 
the oil is rejected and rises to the surface, while the acid 
and the alkali form a new compound. 

185. This affinity is called elective^ because, when one 
substance is mixed with several others it seems to manifest 
a choice between them, and elects one with which it unites, 
to the rejection of the others. 

It is most probable that every substance has an affinity 
for many other substances. We know, indeed, that this is 
true in a great variety of instances, since experiment shows 
that one substance will form several compounds with other 
substances, in succession, and that these compounds may 
in succession be destroyed by the application of other sub- 
stances which have a stronger affinity to the first. 

1 86. As an example, suppose sulphuric acid, or the oil 
of vitriol, to be the first substance, or the one towards which 
several other substances have a chemical attraction, but in 
d-'fferent degrees of force, then a compound formed between 
the acid and the substance having the least affinity, will 
be destroyed by the substance having the next stronger 
degree of affinity, and this second compound would be 
decomposed by the substance having the next degree of 
affinity, and so of every substance having a stronger at- 
traction for the acid. 

Thus, sulphuric acid has an affinity for harytes^ strontian, 
polish, soda^ lime, ammonia, and magnesia, and the force of 
this affinity is in the order in which they are named ; that 
is, barytes has the strongest and magnesia the weakest. 
A compound, therefore, of magnesia and sulphuric acid 
would be decomposed by the addition of ammonia, and 
one of ammonia and ih» acid, by the addition of hme, and 
so on; but none of these substances would decompose that 

Give an example of the exereise of this kind of affinity. "W^en water ia 
poured into a solution of camphor in spirit, why is the camphor separated? 
VVhal is the composition of soap? "Wlien an arid i^ mixed with a solution 
of soap, why does the oil rise to the surface? Why is this kind of affinity 
called elective? What is said relative to the attraction of one substance for 
many others? What are the substances named, as having an affinity for 
■ulpliuric acid, and in what order is the force of this affinity with respect to 
the substances ? 



DOUBLE ELECTIVE AFFINITY. 85 

formed between the acid and barytes, because these sub- 
stances have the strongest affinity for each other. 

187. No chemical facts appear on first view more simple 
or intelhgible than those which are explained by the 
operation of elective affinity. But we shall find on a 
more minute examination, that this force, abstractedly 
considered, is only one of several causes, which are con- 
cerned in chemical decompositions, and that its action is 
modified, and sometimes subverted by counteracting causes, 
to be mentioned hereafter. 

DOUBLE ELECTIVE AFFINITY. 

188. This takes place whenever two compounds, each 
consisting of two ingredients, mutually decompose each 
other, and by a double interchange of these principles form 
two new compounds. We have seen that in single 
elective affinity, one new compound is formed by the 
addition of a single substance, while the ingredient thus 
rejected remained uncombined, or alone, in the solution. 
Thus, when Hme is added to a compound of magnesia and 
sulphuric acid, the lime and acid unite, while the magnesia 
is rejected, and remains sohtary in the solution, having 
nothing on which to bestow its affinity. 

189. In double elective affinity, an interchange of the 
principles belonging to each compound is effected, and thus 
the old compounds are destroyed, and new ones formed; 
and it is curious and interesting to observe the consequences 
of what we should call the likes and dislikes of the parti- 
cles of matter for each other, were they animated. 

190. It often happens, that a compound of two ingredi- 
ents cannot be destroyed by the application of a third, or 
fourth ingredient, separately ; but if the third and fourth be 
combined, and then the two compounds be brought into con- 
tact with each other, decomposition and interchange of prin- 
ciples will ensue. Thus, sulphate of soda is composed of 
soda and sulphuric acid, and is the substance called Glau- 
her's salt. Now, when lime is added to a solution of this 
salt, there ensues no decomposition, because the soda at- 
tracts the acid more strongly than the acid attracts the 
lime. If muriatic acid be added to the same solution, there 

Suppose sofla and sulphuric acid to be combined, which of the substances 
named would decompose the compound ? Which of the substances named 
would decompose sulphate of barytes ? When does double elective affip 
ity take place ? 



86 



DOUBLE ELECTIVE AFFLMTY. 



Still follows no decomposition, because the sulphunc acid 
has a greater affinitj^ for the soda, than the soda has for the 
muriatic acid. But if the lime and muriatic acid be pre- 
viously combined, forming a muriate of lime, and this com- 
pound be added to the solution of the sulphate of soda, 
then a double decomposition follows, and two new com- 
pounds are formed out of the old ingredients. The lime of 
the muriate of lime, and the sulphuric acid of the sulphate 
of soda, having stronger aifections for each other than the 
first has for muriatic acid, or the second for soda, mutu- 
ally abandon their old connections, and having combined 
with each other, form a new compound under the name of 
sulphate of lime. The soda and muriatic acid being 
thus rejected, and their former unions dissolved, they com- 
bine themselves anew, and form another compound, known 
under the name of muriate of soda, or common salt. These 
changes will perhaps be better understood by the diagram 
which follows: 

Muriate of Soda. 



Muriate 

"f 

Lime. 



Sulphate of Lime. 

On the outside of the vertical brackets are placed the 
names of the orignial compounds, sulphate of soda and 
muriate of lime, and above and below the diagram those of 
the new compounds. The upper line is straight, to indicate 
that the muriate of soda remains in solution, while the mid- 
dle of the lower one is directed downward, to show that the 
sulphate of lime is precipitated, or falls to the bottom of the 
vessel. 





Soda. Muriatic acid. 


sulphate 

of ^ 

Soda. 


y 




Sulphuric acid. Li?ne. 



In this kind of affinity, how many old compounds are destroyed, and how 
many new ones formed at the same time? Why does not litne decompose 
sulphate of s» la ? Why does not muriatic acid decompose sulphate of soda ? 
What are the chemical changes effected when muriate of lime is added to a 
solution of sulphate of soda ? What are the names of the compounds formed 
by the decomposition of sulphate of soda and muriate of lime ? Explain the 
diagram illustrating these changes. 



HEAT. 87 



CAUSES WHICH COUNTERACT OR MODIFY THE EFFECTS 
OF CHEMICAL AFFINITY. 

191. ft has been'stated that the effects of chemical ac- 
tion are often modified, or even subverted, by counteracting 
causes. The principal causes which have a tendency to 
counteract chemical combinations are cohesion, quantity oj 
matter, elasticity^ and gravity. 

COHESION. 

192. By cohesion, we mean that attractive force hy which 
the particles of bodies are kept together, and in consequence 
of which, masses are formed. This force may modify, or 
entirely counteract that of chemical attraction ; for the more 
strongly the particles of any substance are united, the greater 
the obstacle to a chemical union with those of other bodies, 
because the successful effects of affinity depend on a mu- 
tual penetration of particles. Hence the formation of chem- 
ical compounds, with some exceptions, requires that at least 
one of the ingredients should be in the state of a liquid, so 
that the particles of each should have free mutual access. 
Where the affinities are strong, and the cohesion shght, the 
union is effected with considerable energy under such cir- 
cumstances. Thus, masses of carbonate of ammonia, of 
considerable size, will be dissolved by nitric acid ; but when 
the force of cohesion is great, it is a strong barrier to the 
operation of affinity. Thus, a mass of carbonate of lime, or 
marble, will remain for days in an acid, when, were it redu- 
ced to powder, it would be dissolved in a few minutes. 

In all such cases, therefore, mechanical division is re- 
quired before rapid solution, or intense chemical action, can 
be effected. Cohesion being thus overcome, solution is 
readily accomplished, because the solid now presents a 
greater extent of surface to the action of the fluid 



193. Heat is another means of counteracting the cohesion 
of bodies, the repulsive power of caloric being indeed the 
great opposing force of that of cohesion, and provided its 

What are the principal causes which promote or counteract chemical 
changes ? What is meant by cohesion ? How does cohesion prevent solution ? 
Why will the same substance in powder enter into solution more reamlj 
than when in the mass ? What is the opposing force to cohesion "^ 



88 QUANTITY OF MATTER. 

quantity be proportionate to the force of attraction, will so 
overcome it as to render all solid bodies liquid. Different 
substances, it is obvious, require different degrees of heal 
for this purpose. Thus, the cohesive force of such bodies 
as are called liquids, is so counteracted by the heat ol 
ordinary temperatures, as to make their particles easily 
moveable among each other, a circumstance on which their 
liquidity depends. But many of these substances, such as 
water and oil, by the abstraction of heat become solids, 
because then the repulsive force of caloric becomes less 
than the attractive force of cohesion. On the contrary, in 
bodies which we term solids, the attractive force of cohesion 
is greater than the repulsive power of caloric, and hence at 
all ordinary temperatures, their particles are fixed and 
immoveable among themselves, a circumstance on which 
their solidity depends. 

We have stated that the exercise of affinity depends on 
the state of the substances concerned, and that in general, 
one of them must be in a fluid state. In most instances, 
solution is effected in some liquid, as an acid, alcohol, or 
water. But to produce metalhc alloj^s, the metals must be 
brought to a liquid state without changing their properties, 
and this can be effected only by means of caloric. For 
this purpose, it is only necessary that one of the metals, 
viz., that requiring the highest degree of heat, should be 
melted, and the other thrown into this in small pieces. 

QUANTITY OF MATTER. 

194. Experiment teaches that quantity of matter exerts 
an important influence over chemical decompositions and 
solutions. Thus, we know precisely how much sulphuric 
acid, for instance, will neutralize a given quantity of potash, 
when in a free state. But if the same quantity of potash 
be first combined with nitric acid, forming nitrate of potash, 
or saltpetre, then more of the sulphuric acid is required to 
detach this quantity than before, probably, because some 
force is employed to destroy the union previously existing 
between the nitric acid and the potash, and also because 



What is the cause of fluidity in bodies? How rniglit all bodies be made 
fluid? Why does water become solid when caloric is abstracted from itT 
On what does the solidity of bodies depend? What is the only means by 
which metallic alloys can be produced? What is sa^d of the influence ol 
quantity of matter on chemical combinations ? 



ELASTICITY. 89 

the affinity of the two substances for each other diminishes 
when both are nearly saturated. 

In making a solution of a metal in an acid, it may m* 
observed, that the chemical action is much more energetic 
at the beginning of the process then afterwards^ and that 
if no more acid be added, than is just sufficient to dissolve 
the metal, the action finally becomes so feeble as to require 
a day or two to complete the combination. But if, in this 
state, more acid be added, the action again becomes brisk, 
and the metal is soon dissolved. 

ELASTICITY. 

195. Cohesion being found an obstacle to the exercise 
of affinity, it might be expected that the contrary state, 
that is, the absence of cohesion, would facilitate chemical 
combinations ; but experiment determines otherwise. In the 
elastic fluids, such as the gases, and common air, cohesion 
may be considered as entirely wanting. But bodies of this 
kind, though having a strong affinity to each other, show 
little disposition, under ordinary circumstances, to combine. 
Thus, oxygen and hydrogen, though in different electrical 
states, may be mixed together in the same vessel for any 
period of time, without the least symptom of combination. 
The reason of this is probably owing to the distance of their 
particles, which prevents that near approach to each other 
required to come within the sphere of mutual attraction; 
for if the two gases be subjected to pressure by means of 
the httle instrument called a fire pump, Fig. 12, they unite 
with explosive energy. 

196. The elastic property not only opposes the chemical 
union of bodies, but is often an agent by which their decom- 
position is effected when exposed to the influence of caloric. 
Thus, substances containing a volatile and fixed principle, 
are sometimes decomposed by heat alone, because the re- 
pulsive force of caloric removes the elements of the com- 
pound beyond the influence of mutual attraction, and the 
volatile element makes its escape in consequence. Many of 
the salts, composed of an alkali, or a metal, and an acid, and 

Explain how quantity of matter is illustrated by the solution of a metal in 
an acid. Does the elastic state facilitate chemical combinations ? What is 
the most probable reasons that gases having an affinity for each other do not 
unite, when mixed under ordinary circumstances ? How may oxygen and 
hydrogen be made to combine ? How does caloric act to separate a volatd© 
from a fixed principle ' 

r* 



90 CHEMICAL CHANGES. 

wa'cf. are readily decomposed by heat alone. The water 
is liisL turned to steam, and escapes by its elasticity, leav 
ing the salt opake, and as the heat is raised, the acid is con- 
verted into vapor, and escapes in the same manner. 

On the same principle, oxygen is obtained from manga 
nese, from nitre, and several other compounds, where it exists 
as a principle. 

GRAVITY. 

197. When the difference between the weight of the two 
bodies is great, this circumstance opposes their chemical 
combination. Thus, when common salt is thrown into 
water, it sinks to the bottom, where the water soon becomes 
saturated, and will dissolve no more ; but if the water be 
agitated, the whole will soon dissolve. It is found, also, that 
metals differing widely in their specific gravities, when 
melted together, do not mix equally, unless they are stirred, 
because the heavier metal settles to the bottom. 



CHANGES PRODUCED BY CHEMICAL COMBINATIONS. 

198. By chemical combination is meant a union betweei 
two or more substances of different kinds, so intimate that 
they cannot again be separated by mechanical means. 
Thus, if clay or chalk and water be mixed, the mixture will 
for a tim3 be turbid, or opake, but if suffered to stand for a 
day or two, the clay or chalk will settle to the bottom of the 
vessel, and the water above will become transparent. But 
if water be mixed with an acid, or with a salt, or with sugar, 
the union becomes permanent, nor will rest, or filtration, or 
any other mechanical means, separate either of these ingre- 
dients from the water. Hence the distinction between me- 
chanical mixture and chemical union. In the first, no 
affinity between the substances exists, and therefore no union 
takes place, and the chalk or clay falls to the bottom of the 
vessel. In the second, there is a combination between the 
particles of which the substances are composed, owing to 
the affinity existing between them, and hence they are not 

How is the decomposition of a fluid eflfected by heat ? What is said of 
gravity in opposing chemical union? How does common salt, in water, illus- 
trate this principle ? What is said of the coml)ination of metals in this re- 
spect ? What is meant by chemical combination ? \Miat is the distinction 
between mechanical mixture and chemical union ? Why will not chalk and 
water combine permanently ? When water and sugar are mixed, why does 
not the sugar settle to the bottom of the vessel ? 



CHP:MICAL CHANGJ?8 q\ 

separated, excep* by a stronger force than that of the cxis?- 
mg affinity. 

199. I'he char2:es that accompany chemical action arc 
in some proportion to its intensity. In the instances above 
named, where water is mixed with a small quantity of acid, 
or salt, this action is feeble, and the sensible changes pro- 
duced inconsiderable, being only a slightly acidulous, or 
sahne taste, given to the water. But in cases where the 
chemical action is intense, the changes produced in the com- 
bining substances are often great in proportion. Thus, when 
the two gases, oxygen and hydrogen, are burned together, 
their combination is attended with most intense chemical 
action, by which the highest degrees of heat are evolved, 
and at the same time the change produced is no less than 
the condensation of two elastic gases into the fluid water. 

200. Many substances which are highly corrosive, in a 
separate state, become mild, and lose all their acrid quali- 
ties by combination with each other. Sulphuric acid and 
potash, for example, are highly caustic substances. They 
both act with great energy on animal and vegetable bodies, 
producing decomposition and total destruction of texture. 
The acid turns the blue colors of vegetables to red, and the 
alkah turns these colors to green. But on mixing these sub- 
stances together, they entirely destroy the caustic qualities 
of each other, and there results a solid compound, called 
sulphate of potash^ which is mild to the taste, and neither 
acts on animal or vegetable bodies, nor changes the colors 
of the latter. This is called a neutral salt, because the sub- 
stances of which it is composed thus neutralize the active 
properties of each other. 

When the opposing properties of chemical agents are 
thus destroyed by combination, they are said to» saturate 
each other, and it is found that the acrid and caustic quaU- 
ties of all the acids and alkalies are weakened in proportion 
as one is added to the other, until the point of saturation is 
attained, when the compound becomes neutral, and is not 
affected by a further addition of the acid or alkali, which 
forms a part of its composition. 

Is there any proportion between the intensity of chemical action and '<he 
changes produced thereby? What illustrations of this law are given . VV hat 
effect does combination sometimes have on the corrosive properties of bodies? 
Give an illustration of this effect. What is the composition of su..phate of 
potash ? What is a neutral salt ? When are substances said to saturate 
each other ■? 



92 AFFINITY. 

'20" Cnange of Bulk. — A change of hulk is also in man/ 
iiisip.!ices the result of chemical union, so that the two ho<5 
ies alter combination, do not occupy the same space as be- 
fore Thus, when a pint of sulphuric acid is mixed with a 
pint of water, the chemical action is so great as to raise the 
tnermometer above the boiling point, and the resulting com- 
pound will not measure two pints as before the mixture, but 
considerably less 

When zinc and copper are fused together, the resulting 
alloy has a specific gravity greater than the medium spe- 
cific gravities of the two metals, showing that their bulks 
are diminished by the union. The same happens when al- 
cohol and water are mixed; and in general it is found that 
the resulting body, after chemical combination, has a greater 
specific gravity than the mean of its components. 

202. Change of Color. — Another change often produced 
by the exercise of affinity, is that of color. The al- 
loys of any two metals do not exhibit the medium of their 
two colors. Thus, the white metal, zinc, and the red one, 
copper, when melted together, form the yellow compound, 
brass. The colors of the metalHc oxides differ according to 
the quantities of oxygen they contain. The black oxide of 
mercury contains 200 parts of the metal and 8 parts of oxy- 
gen, while the same quantity of metal combined with 16 
parts of oxygen, forms the red oxide of mercury. We have 
already had occasion to notice, that blue vegetable colors are 
changed to red by acids, and to green by alkalies ; and in 
addition to this, we may state generally, that all vegetable 
colors are changed, more or less, by the appUcation of these 
agents. 

203. Change of Form. — There is still another change, 
which is the effect of chemical affinity, and is often highly 
important ; this is the change of form. Of this change 
chemistry exhibits a great variety of examples, many of 
which are highly curious and interesting. Thus, if a satu- 
rated solution of muriate of lime in water, be mixed with a 
small quantity of sulphuric acid, the two fluids immediately 
Decome a sohd. This change is produced by the exercise 

What IS said of change of bulk as a result of chemical action? Suppose 
a quantity of water and sulphuric acid are mixed, will they occupy the same 
bulk that they did before the mixture? Will the bulk be greater or less than 
Defore ? In chemical combinations, is the resulting body more or less dense 
than the medium density of its components ? What is said of the change of 
color produced by chemical combinations ? Is change of form ever effected 
by chemical combinations ? 



AFFINITY. 93 

of affinity. The muriate of lime is composed of lime and 
muriatic acid, and of this salt water will dissolve a la\'(^Q. 
quantity and still remain fluid. The sulphuric acid has a 
stronger attraction for hme than the muriatic has, and the 
sulphate of lime is nearly insoluble in water. When, there- 
fore, the former acid is added to the solution, a sulphate of 
lime is formed, which, in a spongy form, occupies the whole 
vessel. On the contrary, if equal parts of alum and ace- 
tate, or sugar of lead, be rubbed forcibly together in a mor- 
tar, they form a compound mass which is nearly fluid. The 
cause of this change from the sohd to the semi-fluid state, 
is also easily explained. The alum and sugar of lead con- 
tain a quantity of water, called the water of crystallization. 
When they are forcibly rubbed together, the elements of 
which they are composed unite in consequence of mutual 
affinity, and thus the water of crystallization is set free, and 
occasions the partial fluidity of the mixture. The great 
changes which the two gases undergo in the formation of 
water, have already been mentioned. Similar changes, so 
far as respects the condensation of elastic fluids and liquids, 
are phenomena which are frequently witnessed in experi- 
mental chemistry. Thus, water absorbs about 5000 times its 
own bulk of the gas called ammonia, which is in this man- 
ner condensed, and forms a part of the liquid. The com- 
pound thus formed is known by the name of spirit of harts- 
horn. Cluicklime, in the process of slacking, absorbs a large 
quantity of water, which by this combination becomes solid, 
and forms a part of the dry lime. 

204. In the formation of the gases, on the contrary, there 
is an immense increase of bulk. When water is decom- 
posed and made to assume its elementary gaseous form, there 
is an increase of bulk nearly equal to 2000 volumes. That 
is, a cubic inch of water contains 662 cubic inches of oxy- 
gen, and 1325 cubic inches of hydrogen; thus the volume 
is increased 1987 times by the decomposition. The explo- 
sion of gun-powder is another example of the vast increase 
of volume by chemical decomposition. 



How is the change of form accounted for when sulphuric acid and muriate 
)f lime are mixed? How is the change of form explained, when alum and 
icetate of lead are forcibl}' mixed ? What is said of the condensation of 
immonia by water, and the condensation of water by slacking lime ? How 
many times more bulky are the gases of which water is composed, than 
water itself? 



94 AFFINITY. 

m 

FORCED i'CHEMICALAFFINlTY. ■ 

205. Although it is ascertained, by means already de- 
scribed, that the affinity of one body for a number of others, 
IS not of equal force, yet we are ignorant Aow much differ- 
ence there is in the forces of these different degrees of 
affinity. 

206. The only means of deciding this question is to ob- 
serve the tendency which several substances have to unite 
with the same substance, under similar circumstances. 
Oxygen, for instance, as a universal agent, might be selected 
as a standard, and the force of affinity between this and 
other bodies be estimated by their degrees of oxidation under 
the same circumstances. We know that there is an im- 
mense difference between the forces with which different 
bodies attract this principle. Some of the metals, for in- 
stance, absorb oxygen with such avidity, that they cannot 
be preserved in their metallic state when exposed to the 
atmosphere, even for a short time ; while others have so httle 
affinity for this principle, that they cannot be oxidated 
without the most energetic means. Thus, potassium (see 
this word) attracts oxygen with such force as to decompose 
water, at common temperatures, by absorbing it from the 
hydrogen ; while the af^nity of platina, or gold, for this prin- 
ciple is so weak as not to attract it at all, except at the 
highest degrees of heat, or from acids which impart it mos* 
easily. 

207. We may constantly observe the effect of the differ 
ent forces with which several metals attract oxygen in the 
com.mon affairs of Hfe. Thus, iron and lead, when exposed 
to the moisture of the atmosphere, soon tarnish, and after a 
time, by the absorption of oxygen, their surfaces become 
covered with rust, or the oxides of iron and lead. But silver 
and gold, when exposed in the same manner, continue 
bright and untarnished for years, as may be observed in the 
points of hghtning rods, and the gilded vanes and balls of 
church steeples. This difference can only arise from the 
different forces with which these metals attract the oxygen 
of the atmosphere. 

208. There is no department in chemistry, either as a 

How might the force of afBnity be ascertained ? How do we know tha 
there is a great difference between the forces with which bodies attract oxy 
gen? How is this difference illustrated ? How is it shown that iron an 
lead attract oxygen with greater force than silver and gold ? 



PROPORTIONS. . 95 

science, or an art, which so much needs the investig-ation 
of able men as this. Tables of affinity, showing at once the 
force of attraction between different chemical elements, 
would enable the inquirer, without further experiment, to 
decide what substance would decompose any given com- 
pound, and therefore how to separate, or combine, the differ- 
ent principles of bodies for a vast variety of purposes. Tables 
to a very limited extent have already been constructed for 
such purposes, but the difficulty and magnitude of this sub- 
ject seems to have deterred the more modern chemists from 
engaging in this extensive department of the science. 

INDEFINITE AND DEFINITE PROPORTIONS. 

209. It is ascertained by experiment that some bodies 
unite in unlimited, or indefinite proportions, while others 
combine in proportions which are always limited or definite. 

The discovery of the laws of definite proportions is one of 
the most important and wonderful among the great and bril- 
liant achievements in m^odern chemistry. It is sufficient of 
itself to convince any reasomng mind, that order and system 
pervade the universe, and that the minutest atoms of matter, 
and the vast orbs that move round the heavens, are equally 
under the control of the invariable laws of the Creator. 

INDEFINITE PROPORTIONS. 

210. When we mix water and alcohol, or water and any 
of the acids, they unite in any proportion. Thus, a drop of 
acid will combine with any quantity of water, and water 
will unite in the same manner with alcohol, or acid. This 
principle may be tested by direct experiment ; for if a gallon 
of water be tinged blue by a vegetable color, a few drops of 
sulphuric acid will turn every drop in the gallon to a red 
color, thus proving, that this small quantity of acid has 
diffused itself through the whole mass. By similar experi- 
ment it can be shown that a small quantity of water will 
diffuse itself through a large quantity of acid. These exam- 
ples prove that some bodies combine in unlimited proportions 
on both sides. 

Other combinations appear to be limited on one side, and 

What would be the use of tables, showing the force of attraction betwec n 
different chemical elements? What is said of the discovery of the laws of 
definite proportions ? What substances are mentioned, which combine in 
unlimited proportions '^ 



96 PROPOKTiONS. 

unlimited on the other. Thus, common salt, and other 
saline substances, will dissolve in water in any proportion 
short of the point of saturation, after which, ii" more be added, 
it will fall to the bottom of the vessel and remain solid. The 
greatest proportions in which water and connnon salt com- 
bine, are those of 100 of the former, with 40 of the latter; 
but the smallest quantity of salt will diffuse itself through 
the largest quantuy of water, and the probable reason whj'- 
salt does not unite with water in every proportion, is, that 
its cohesion resists the feeble affinity of the fluid after it be- 
comes saturated. 

211. In all cases where bodies combine with each other 
in every proportion, or where the proportions are limited on 
one side, and indefinite on the other, the force of affinity by 
which such compounds are formed is feeble, and the com- 
pounds themselves often differ but little from the original 
ingredients. Thus, alcohol and water combine in all pro- 
portions, but the union produces only a modification of the 
qualities of each, the degrees of which depend on the pro- 
portions of the mixture, and the force of affinity between them 
is so weak, that distillation, by a gentle heat, entirely de- 
stroys their union. Solutions of the salts, sugar, acids, and 
many other principles, are examples of the same kind : a 
moderate heat, and sometimes evaporation, without heat, 
will dissipate the water and leave the other ingredients in 
their former state. 

In these, and a great variety of other instances, although 
the force of affinity is slight, still there is a wide difference 
between such compounds, and mere mechanical mixtures, 
since the latter are separated by rest, while the ingredients 
of the foraier are not separated by rest, filtration, or any 
other mechanical means. 

These solutions, or combinations, formed by feeble affini- 
ties, resemble mixtures in respect to the slight changes which 
their ingredients undergo by uniting, while they resemble 
chemical compounds in respect to the inseparable nature of 
the union, by mechanical means. 

How is it proved that a few drops of acid will diffuse itself through a larg?, 
quantity of water ? What bodies combine in limited proportions on one side, 
and unlimited proportions on the other ? In what proportions do water and 
common salt combine? In cases where bodies unite in all proportions, is 
the force of affinity strong or weak? What are the substances mentioned 
which unite in all proportions ? In what respect do combinations, formed by 
feeble affinities, resemble mixtures, and in what respect do they resemble 
chemical compounds ? 



PROPORTIONS. 97 

212. The writer of the article Chemistry^ in the Library 
of Useful Knowledge, has called such slight combinations 
chemical mixtures^ in order to distinguish them from com- 
pounds fonned bj energetic affinities, and which come 
within the law of definite proportions. 

But as the student will find in most books on this subject, 
that mixtures are distinguished from compounds only by the 
means necessary to separate their ingredients, we have 
thought best, at present, to continue the same division ; at 
the same time, having it distinctly understood, that the uni- 
versality of definite proportions, applies only to energetic 
combinations. 

DEFINITE PROPORTIONS. 

213. By definite proportions in chemistry, it is meant that 
the ingredients, or elements of chemical compounds, unite 
with each other in certain proportions only ; and that these 
proportions in the same compound, are, under all circum- 
stances, invariably the same. The proofs of this doctrine 
are established by experiments conducted with the most 
rigid exactness, and, it is true, beyond all controv^ersy. 

The subject of definite proportions may be conveniently 
treated of under three several propositions or laws, it being 
understood that the proportion of hydrogen in water repre- 
sents unity, or 1, and that this is the common unit to which 
all the other numbers refer. 

214. First, TJie composition of all chemical compounds is 
fixed and invariable. 

Experiment shows, that some bodies combine in only one 
proportion. Thus, there is only one compound of zinc 
and oxygen, called the oxide of zinc. Other bodies com- 
bine in two proportions. Thus, there are two oxides of 
copper, one of which is composed by weight of 1 proportion 
of oxygen and 8 of copper, and the other, 2 of oxygen, 
and 8 of copper. Other bodies, again, combine in three, 
four, five, or even six proportions ; the latter being the 
greatest number of compounds known to have been formed 

^^Tiat are these slight combinations called in the Library of Useful Know- 
ledge? What is meant by definite proportions in chemistry? What is the 
first law of definite proportions? What two substances combine only in one 
proportion? What two substances are mentioned which combine ;q two 
proportions, and what are these proportions ? What number of compounds 
are known to be formed by two elements ? The proportions of any chemicaJ 
compound being definite, what would be the effect of changing these propor 
tions ? 

5 



98 PROPORTION'S. 

b}' urjy two substances, within the Hmits of definite propoi 
tions. 

'I'he proportions of any given compound being invariably 
the same, it follows that its characteristic properties depend or. 
these proportions, and that if these proportions are changed, 
the compound will contain new properties, and there- 
fore a new substance is formed. As an example of the 
change produced on the compound, by a different propor- 
tion of one its constituents, we will cite mercury and chlo- 
rine, (See Chlorine.) These two substances unite in two 
proportions, the first of which is composed of mercury 200, 
and chlorine 36. This forms the well know medicine called 
calomel^ and is sometimes given in doses of a tea-spoonful at 
a time, without injury. The other is composed of mercury 
200, and chlorine 72, being one more proportion of chlorine 
than is contained in the calomel. But the two compounds 
in their sensible qualities are entirely different, the latter be- 
ing one of the most active and fatal of poisons, and is known 
by the name of corrosive sublimate. Thus, two substances 
uniting in one proportion, form a compound which is com- 
paratively inert, while in another proportion they form one 
of the most virulent poisons known. Nor is there any me- 
dium, or half-way union between these bodies ; they com- 
bine in these two proportions or not at all. For, suppose 
200 parts of mercury should be exposed to the action of 40 
parts, by weight, of chlorine, then the mercury would com- 
bine with 36 parts of the gas, and no more, leaving the other 
4 parts remaining untouched. And so, on the contrary, if 
210 parts of the metal be exposed to the action of 36 parts 
of the gas, then the gas will combine with 200 parts of the 
mercury, while the 10 parts would remain uncombined. 

In all energetic combinations the proportions of the com- 
bining substances are limited in the same manner, though 
the proportions themselves are exceedingly various. Indeed, 
it appears that the law of limited proportions is as universal 
and as permanent as the law of gravitation itself and that 
its doctrines, so far from being founded on the theoretical 
opinions of men, are in truth based on a general, but more 
recently discovered law of nature. 



What example is given of the difference between compounds formed of one 
and two proportions of the same elements ? What is said concerning the 
combination of mercury and chlorine in other proportions 1 Will 40 parts 
of chlorine unite with 200 parts of mercury? On what is it said the truth ol 
the Jaw of definite proportions is founded ' 



PROPORTIONS. 99 

215. Second. When two substances unite in more than 
ene proportion^ the second or third proportions are multiples oj 
the firsts by a whole number. 

This very remarkable law applies in every case where 
bodies unite with each other in more than one definite pro- 
portion. The expression of the law simply means, that the 
first proportion in which two bodies unite, is in the lowest or 
smallest proportion in which the two constituents are capa- 
ble of uniting with each other, and that the other proportions 
are double, triple, or quadruple, this lowest proportion. 

For example, the several compounds of nitrogen and oxy- 
gen are in the following proportions to each other, viz. : 

Nitrogen. Oxygen. 

Nitrous oxide, consists of 14 parts and 8 parts. 
Nitric oxide, " 14 " 16 " 

Hyponitrous acid," 14 " 24 " 

Nitrous acid, " 14 " 32 '' 

Nitric acid, " 14 " 40 " 

Thus the lowest proportions in which oxygf ti and nitrogen 
combine, being to each other as the numbers 8 and 14, all 
the other proportions of oxygen are multiples of this first 
number, while the proportion of nitrogen remains the same. 
The second number is the first multiplied by 2 ; the third, 
the first multiphed by 3 ; and so on. These proportions are 
therefore to each other, as the numbers 1, 2, 3, 4, and 5. 

Illustrations of this law can be observed throughout every 
department of chemistry, where the analysis of chemical 
compounds are given, and with a single exception, or two, 
where it is most probable the fault is either in the analysis 
or the want of knowledge, the same principle is found to be 
exactly true. One of these exceptions is found in an oxide 
of manganese, and will be pointed out hereafter. 

On these discoveries is founded the law called the law of 
multiple proportions^ a phrase which is often repeated in all 
the late works on Chemistry, and of its general truth, as 
already observed, there can be no doubt. . In the above ex- 
ample, all the succeeding proportions of oxygen are multi- 
ples of the first. 



What is the second law of definite proportions ? What explanations are 
given of this law ? Suppose the smallest proportions in which nitrogen and 
oxygen combine are 14 of the first, and eight of the last by weight, what then 
will be the second proportion in which oxygen combines witn nitrogen ? 
What the third, what the fourth, and what the fifth ? 



UMi PROPORTIONS. 

2 16. Third. The third law of combination is nearly con- 
necled with the last, though the difterence of expression and 
of meaning will be obvious. This law is not less extraor- 
dinary than that of multiple proportions, and may be under 
stood by the following examples given by Dr. Turner. 

Water, we have already seen, is composed of 8 oxygen 
and 1 hydrogen; hj^DOsulphurous acid is composed of 8 
oxygen and 1 6 sulphur. Now, it is a curious fact, that the 
gas called sulphuretted hydrogen, is constituted of 1 hydro- 
gen and 16 sulphur ; that is, the quantities of hydrogen and 
of sulphur which combine with the same quantity of oxy- 
gen, combine with each other. Again, 36 parts of chlorine 
and 8 of oxygen constitute the oxide of chlorine, and with 
1 of hydrogen, form muriatic acid gas : also, 1 6 parts of sul- 
phur combine with 36 of chlorine to form the chloride of 
sulphur. Hence bodies unite in proportional numbers, as in 
the above instances the proportion of hydrogen is 1, that of 
oxygen 8, that of sulphur 16, and that oi chlorine 36. 

But this law not only applies to the elementary parts of 
substances, such as hydrogen, oxj^gen, chlorine, and sul- 
phur, but also to compound bodies, whose combining pro- 
portions may likewise be expressed by numbers. 

217. Now, the proportions of any compound being ex- 
pressed by the numbers attached to each element of which 
it is composed, the number representing the compounds is 
composed of the sum of its parts, or elements. Thus water 
is composed of oxygen 8, hydrogen being 1, and its com- 
bining proportion will therefore be 8+1=9. When one 
element combines w4th another in several proportions, the 
number representing the single proportion, and those repre- 
senting the several other proportions, are added together to 
make up the combining number of the compound. Thus, 
sulphuric acid is composed of one proportion of sulphur 16, 
and three proportions of oxygen ; and as one proportion of 
oxygen is 8, so the whole number representing the oxygen 
in this acid is 24 ; to which 16 being added, makes the num- 
ber representing sulphuric acid to be 40. 

What is the third law of definite proportions ? Explain this law. Suppose 
64 represents the metal, and 8 the oxygen, in an oxide of copper, and suppose 
there is a second oxide, what would be the numbers representing the metal 
and the oxygen? Does this law of numbers apply to the elements of bodies 
only, or to the compounds also? When the numbers for the elements of a 
compound are known, how may the number for the compound be found ^ 
What are the numbers for hydrogen and oxygen in water? 



DEFINITE PROPORTIONS. 101 

218. It must be remembered that the smallest proportion, 
by weight, in which an element is found to combine, is tne 
fixed number by which that element is always represented. 
Oxygen is invariably represented by 8, because this is the 
smallest proportion in which it is known to combine with 
any other substance. Thus, also, water is composed of 
oxygen 8, and hydrogen 1 ; potash of oxygen 8, and the 
metal, potassium 40. The lowest proportion in which sul- 
phur is known to combine with any other substance is 16, 
and therefore sulphur is always represented by this number. 
Thus sulphuret of lead is composed of 1 proportion of sul- 
phur 16, and one of lead, whose combining number is 104. 
Its number therefore is 1 6+ 104 = 120. We have just men- 
tioned that the combining number of any compound is repre- 
sented by the sum of its simple, or elementary parts. This 
will now be understood ; for by adding the numbers repre- 
senting the elements in each of the above examples, we shall 
have those by which the compounds are represented. The 
number for water, as already shown, is 9 ; the number for 
potash is 48, viz. 8 oxygen, and 40 potassium ; that for sul- 
phuret of lead is 120, viz. sulphur 16, and lead 104. 

219. By remembering the combining weights of the 
elements of any compound, the number representing that 
compound may at once be known. For example, hydrate 
of potash is composed of water and potash ; water is com- 
posed of oxygen 8, and hydrogen 1 =9. Potash is com- 
posed of potassium 40, and oxygen 8=48. These two 
smus being added, viz. 9 + 48 = 57. Thus the number for 
hydrate of potash is 57. Again, the salt called sulphate of 
potash is compounded of sulphuric acid and potash. Now, 
to find the number representing its combining proportion, we 
have only to remember that sulphuric acid is composed of 
one proportional of sulphur 16, and 3 proportionals of oxy- 
gen 24, and that the sums of these two numbers are 40. 
The number for potash, as above seen, is 48 ; therefore the 
number for sulphate of potash, being the sum of these two 
numbers, is 40 + 48 = 88. 

What then is the number for water? How does it appear that 40 is the 
number for sulphuric acid ? Are the numbers for each element and compound 
invariable ? On what circumstance is the number for an element founded? 
What is the number for sulphuret of lead ? What other numbers is this num- 
ber composed of? Hydrate of potash is composed of water and potash, how 
will you find the number which represents hydrate of potash ? What is the 
composition of sulphate of potash? How may the number representing this 
compound be found ? 



102 DEFINITE PROPORTIONS. 

It is unnecessary to adduce further examples, since the 
intelligent student will be able to understand from the 
above epitome, not only on what kind of facts the laws of 
definite proportions are founded, but will also, it is hoped, 
be able to apply the above principles to the proportional 
numbers of the most common substances to be mentioned 
hereafter. 

COMBINATION BY VOLUMES. 

220. The doctrine of definite proportions was founded on 
the suggestions of Mr. Higgins, of Glasgow, published in 
1789. But it was Mr. Dalton, of Manchester, in England, 
who established the laws of chemical combinations, and 
who has the merit, of not only discovering almost all that 
is known in the details of this subject, but also of having 
brought it distinctly before the world. Mr. Dalton pub- 
lished his \dews of the doctrine of definite proportions in 
1808, soon after which. Gay Lussac, a French chemist, 
proved, by a publication in one of the journals, that gases 
unite in simple and definite proportions, and among other 
instances, showed that water is composed precisely of 100^ 
volumes of oxygen, and 200 volumes of hydrogen. It was af- 
terwards shown, by the same author, that other gaseous sub- 
stances, which are capable of a chemical union with each 
other, unite in definite proportions, by measure, or volume, 
and that these proportions are in the simple ratio of 1 to 1, 
1 to 2, 1 to 3, and so on, as above stated. 

221. These obsei^ations have since been confirmed by 
numerous experiments, instituted by the first chemists of 
the age, and at present it is as fully estabhshed, that the 
law of definite proportions extends to the volumes of gases, 
as it does to their weights, and to those of solids. As an 
illustration of the truth of this law, we adduce the conden- 
sation of hydrogen and oxygen by combustion, because 
these gases are more generally known than any others, 
and because their combination is also one of the most 
familiar examples of definite proportions by weight. The 
apparatus for this purpose it is unnecessary to describe, it 
being sufficient for our present purpose to state that the 

Who first suggested the doctrine of definite proportions ? Who extended 
this subject, and brought it before the public ? What is said relative to the 
union of the gases by volume ? In what ratio do the gases combine by vol- 
ume ? What illustration is given of the union of the gases by volume ? What 
are the proportions in which hydrogen and oxygen combine by volume, and 
w^hat are these proportions by weio^ht^ 



DEFINITE PROPORTIONS. K)^ 

experiment has often been made with the most mf^lHble 
accuracy. 

222. The invariable proportions in which oxygen and 
Hydrogen combine, are, by vohune, 1 of the first, and 2 of 
the last, and by weight, 16 of oxj^gen to 1 of hydrogen. 
Thus, the specific gravities of these two gases are to each 
other as the numbers 1 and 16, that is, a cubic foot of 
oxygen is just 16 times as heavy as the same bulk of 
hydrogen. The reason why hydrogen is represented by 1, 
as its combining proportion, by weight, while its combining 
volume is double that of the oxygen, will be seen hereafter. 
The mode of ascertaining the comparative volumes in 
which these two gases combine, is to measure them care- 
fully, and having introduced them into a glass tube, the 
mixture is inflamed by an electric spark ; and in every in- 
stance it has been found, that whatever the proportions of 
the mixture might be, in respect to each other, the ratio of 
combination is always the same, and consists of two parts 
of hydrogen, and one of oxygen, by volume. When one 
measure of oxygen is mixed with three of hydrogen, there 
will remain in the vessel one measure of hydrogen uncom- 
bined and pure, and no continuance of the electricity will, 
in the least, change this proportion ; and so, two measures 
of oxygen and two of hydrogen, leave one measure of 
oxygen in the same manner. 

223. When other gases unite, merely in consequence of 
being brought into contact, and without combustion, the 
same law applies ; that is, if the volume of one be greater 
than its combining proportion, the excess remains pure and 
untouched. 

We give a few examples of the proportions in which 
gases unite by volume : 

Volumes. Volumes. 

100 muriatic acid gas combine with 100 ammoniacal gas, 
100 oxygen gas " 200 hydrogen gas, 

100 hydrogen gas " 50 oxygen gas, 

100 nitrogen gas " 200 oxygen gas, 

100 chlorine gas " 100 hydrogen gas, 

100 nitrogen gas " 300 hydrogen gas. 

What are the relative specific gravities of these tw^o gases ? What is the 
mode of ascertaining the volumes of these gases ? Suppose one measure of 
oxygen is mixed with three of hydrogen, and inflamed, what will become of 
the third measure of hydrogen ? Does the same law apply when two gases 
combine without combustion ? What illustrations are given of the conibina 
tion of gases by volume '^ 



104 CHEMICAL EQUIVALENTS. 

Another curious fact concerning the union of the gases 
is, that many of them suifer a diminution of bulk, which is 
also in a simple ratio to the volume of the one or both 
Thus, when 3 volumes of hydrogen and 1 of nitrogen com- 
bine, they instantly contract into 2 volumes, or one half 
their former bulk, and form gaseous ammonia. A similar 
condensation takes place when several of the other gases 
combine. 

CHEMICAL EQUIVALENTS. 

224. It was long since proved by Wenzel, a German 
chemist, that when two neutral salts decomposed each 
other, the resulting compounds are likewise neutral. That 
is, the acid of one will exactly neutralize the alkali of the 
other; and although two new salts are formed by this 
mutual decomposition, they will both, like the original 
compounds, be equally neutral. If one of the salts be in 
quantity too large for the combining proportions, then the 
excess of that salt will remain undecomposed in the solution, 
and only such a portion of it will be decomposed as is just 
sufficient to neutralize the constituents of the other salt. 

225. Hence, Chemical Equivalents are those definite pro- 
portions of one substance^ which neutralize definite proportions 
of another substance. 

The truth of this law may be demonstrated by setting 
down the combining numbers of two salts, and the number 
representing the two new compounds, and then by ex- 
changing the numbers representing the combining parts, the 
numbers for each compound will be found to represent the 
number for the new compound, and the combined numbers 
of the old and new compounds will be equal to each other. 
Thus, the number for sulphuric acid is 40, and the com- 
bining proportion of potash is 48, and therefore the number 
for sulphate of potash is 88. The combining proportion ot 
nitric acid is 54, and that of baryta 78, and the sum of these 
two numbers is 1 32, which represents the nitrate of baryta. 
Now, when these two salts are mingled together in solution, 
both are decomposed ; the 54 parts of nitric acid of the 
nitrate of baryta will saturate the 48 parts of potash of the 

What is meant by chemical equivalents ? How may it be proved that when 
t\NO salts decompose each other, the acid of one exactly neutralizes the alkali 
of the other? What number represents nitrate of baryta? What number 
represents sulphate of potash ? When these two salts decompose each other, 
wnat are the names of the new salts formed, and what is the number for each? 



CHEMICAL EQUIVALENTS. 105 

sulphate of potash^ making a new salt, nitrate of potash^ 
whose combining number is 102. At the same time, the 40 
parts of sulphuric acid of the sulphate of potash will combine 
with, and saturate, the 78 parts of the baryta of the nitrate 
of baryta^ forming another new salt, sulphate of baryta^ 
whose number will therefore be 40 added to 78 = 118. 

Now, it may be observed that the sums of the proportional 
numbers of the old and new compounds are equal, and the 
same, and therefore that there can be no excess in either of 
the alkahes or acids. This may be shown thus : 

Sulphuric acid 40 and potash 48, form sulph. potash, 88 
Nitric acid 54 and baryta 78, form nitrate baryta, 132 

Sum of the old compound, 220 

Sulph. acid 40 and baryta 78, form sulph. of baryta, 118 
Nitric acid 54 and potash 48, form nitrate of potash, 102 

Sum of the new compound, 220 

226. The utility of being acquainted with these important 
laws, says Mr. Turner, is almost too manifest to require 
notice. Through their aid, and by remembering the pro- 
portional numbers of a few elementary substances, the com- 
position of an extensive range of compound bodies may be 
calculated with facility. By knowing that 6 is the com- 
bining proportion of carbon, and 8 of oxygen, it is easy to 
recollect the composition of carbonic oxide, and carbonic 
acid; the first being composed of 6 carbon and 8 oxj^gen, 
and the second of 6 carbon and 16 oxygen. By simply re- 
membering, therefore, that carbonic oxide is composed of 
one proportion of carbon, and 1 proportion of oxygen, and 
knowing that carbon is represented by 6 and oxygen by 8, 
we at once arrive at its composition. And by recollecting 
that carbonic acid has 1 proportion of carbon, and 2 of oxy- 
gen, the composition of this is also known. It may be re- 
membered that the number for potassium is 40, and that 
when combined with one proportion of oxygen 8, it forms 
potash 48. Now, by remembering these data, we know, 

What is the sum of the numbers of the old salts, and what the sum of tne 
numbers of the two new salts ? What is the equivaler* number for carbon? 
What is the equivalent number for oxygen ? Carbonic acid is composed of 1 
equivalent of carbon, and 2 equivalents of oxygen, now what is the numbei 
for carbonic acid? 

5* 



lOG CHEMICAL EQUIVALENTS. 

without further trouble, the composition of the carbonate and 
bicarbonate of potash. The carbonate being composed of one 
proportion of carbonic acid, 22, (that is, 6 carbon and 16 
oxygen,) and one proportion of potash 48, (that is, potassium 
40 and 8 oxygen,) is represented by 70. The bicarbonate 
is composed of one proportion of potash 48, and two of car- 
bonic acid 44, and its number is, therefore, 92. 

227. Again, having in the memory the numbers repre- 
senting carbonic acid, we can readily apply them to the 
composition of other compounds, with which this acid is 
united. Thus, the nmnber for carbonate of soda is 54, and 
we know from its name (see Nomenclature,) that it con- 
tains only one proportion of carbonic, acid. Now, by recol- 
lecting the combining proportion of sodium, we know, in a 
moment, the composition of the carbonate of soda. The 
combining number for carbonic acid being 22, this sub- 
tracted from 54, leaves 32 for the other combining pro- 
portion, and knowing that 24 is the number for sodium, 
and that soda is composed of sodium and oxygen, and that 
the combining number of oxygen is 8, we ascertain the 
composition of the salt in question : viz., sodium 24, oxygen 
8 = 32 soda ; carbonic acid 22 = 54 carbonate of soda. 

By the same law of proportions, suppose it is required to 
find the composition of sulphate of soda. The composition 
and number of soda being known, we have only to remem- 
ber that the combining proportion of sulphur is 16, and that 
sulphuric acid is composed of one proportion of sulphur 
and 3 of oxygen, and the composition of this salt and its 
number is ascertained. Soda 32, sulphur 16 ; oxygen 3 
proportions, 24, 16 = 40 added to 32 = 72. Therefore the 
number for sulphate of soda is 72, and its composition 32 
of soda and 40 of sulphuric acid. 

Thus by the application of this law to the combining 
numbers, or the equivalents of chemical bodies, a table of 
which may be found at the end of this work, the composi- 
tion of most compounds may be readily ascertained. 

METHOD OF ASCERTAINING TH E EQUIVALENT NUMBERS 
OF COMPOUNDS. 

228. The combining numbers of all the elementary bodies, 
as already stated, represent the smallest proportions in which 

Why is the number, or equivalent, of carbonate of potash 70? Why is bi- 
carbonate of potash represented by 92 ? Why is carbonate of soda repre 
sented by 54 ? 



CHEMICAL EQUIVALENTS. 107 

they are severally found in union with any other body. But 
it is obvious that all these numbers must have one common 
unit from which thej^ are calculated, otherwise there would 
exist no proportions between them. For this purpose, 
hydrogen, as uniting in the lowest possible proportion, is 
emploj^ed. Thus, hydrogen unites with oxygen in one 
proportion, by weight, to form water, and the weight of 
hydrogen being 1, the weight of oxygen in water is 8, which 
is ^Iso the smallest proportion in which the latter body is 
found in union. 

These two elements, having an extensive range of affinity, 
and therefore being found in combination with a great variety 
of other substances, are made the data, or points of com- 
parison, from which all the other numbers are calculated. 

Afterwards, other compounds were examined which con- 
tained the smallest proportions of these elements united to 
other substances. Among these it was found that the gas 
called carbonic oxide^ contained the smallest combining pro- 
portion of carbon, united with the smallest proportion of 
oxygen, these proportions being as 6 to 8. And also, that 
the gas called sulphuretted hydrogen^ contained the smallest 
proportion of hydrogen united to the smallest of sulphur, 
these proportions being I of hydrogen and 16 of sulphur. 

Thus, the numbers for carbon and sulphur were found to 
be 6 for the former and 16 for the latter, the numbers for 
hydrogen and oxygen being 1 and 8. 

On examination of the different oxides of iron, it was 
found that the least proportion with which that metal com- 
bined with oxygen, was that of 28 of the former, and 8 of 
the latter. The number for iron is therefore 28, and that of 
this oxide of iron 32. 

In this manner the proportional numbers of each com- 
pound has been ascertained, and from these, tables of chemi- 
cal equivalents have been constructed. 

229. In the above epitome of the doctrine of chemical 
equivalents, we have adhered to the practice of giving whole 
numbers to the combining proportions, as being sufficiently 
near the truth for all common purposes, and by far less 

By the same law of proportion, show why the equivalent for sulphate of 
joda is 72 ? What are the units, or data, from which the combining numbers, 
ar equivalents, are calculated ? Having the numbers for hydrogen and oxygen 
as data, how are the numbers for other bodies found ? What are the equiva 
lent numbers for carbon and sulphur? Explain how the number for iron was 
found. 



JUS 



CHEMICAL EQUIVALENTS. 



perplexing to the student than to add the decimal parts 
indicating the exact compositions. Thus it may readily be 
remembered that the combining number for gold is 200, 
while 199.2, the exact proportion for that metal, would as 
readily be forgotten, and so of carbon, aluminum, and others, 
where some late writers have chosen to distract the pupil 
by adding the decimals, in all cases, where they occur in 
the definite numbers. 

In giving whole numbers only, as definite proportions, we 
have the authority of Sir Thomas Brande, from whose recent 
work the following: table is extracted : — 



23Q TABLE OF SIMPLE SUBSTANCES WITH THEIR 
EQUIVALENT NUMBERS, HYDROGEN BEING 1. 



1. Aluminum 10 

2. Antimony 65 

3. Arsenic 38 

4. Barium 69 

5. Bismuth 72 

6. Boron 20 

7. Bromine 78 

8. Cadmium 56 

9. Calcium 20 

10. Carbon 6 

11. Cerium 48 

12. Chlorine 36 

13. Columbium 185 

14. Chromium 28 

15. Cobalt 30 

16. Copper 32 

17. Fluorine 18 

18. Glucium 18 

19. Gold 200 

20. Hydrogen 1 

21. Iodine 125 

22. Iridium 96 

23. Iron 28 

24. Lead 104 

25. Lithium 10 

26. Magnesium 12 

27. Manganese 28 



28. Mercury 200 

29. Molybdenum .... 48 

30. Nickel 28 

31. Nitrogen 14 

32. Osmium 100 

33. Oxygen 8 

34. Palladium 54 

35. Phosphorus 16 

36. Platinum 96 

37. Potassimn 40 

38. Rhodium 45 

39. Selenium 40 

40. Silicium 8 

41. Silver llO 

42. Sodium 24 

43. Strontium 44 

44. Sulphur 16 

45. Tellurium .'.... 32 

46. Thorinum ..... 60 

47. Tin 58 

48. Titanium 24 

49. Tungsten 100 

50. Vanadium 68 

51. Uranium 217 

52. Yttrium 32 

53. Zinc 32 

54. Zirconium 30 



231. Only ffty-four known elements. — Every substance 
upon our globe, so far as is yet known, is composed of one 
or more of the simple bodies contained in the above cata- 
logue. Some of them, as vanadium, and uranium, are of 
very rare occurrence, while others, as aluminum, iron, and 
calcium, are very abundant in nature, though combined witb 
other substances. It will be observed that by far the great- 
est number of them come under the denomination of metals. 



CHEMICAL EQUIVALENTS. 



109 



though several of these, as potassium, calcium, and sodium, 
cannot be obtained in a separate state, without the most 
refined and powerful chemical aid. Among them all, the 
most common and abundant in nature are oxygen, hydro- 
gen, carbon, and nitrogen, as it will be remembered, that 
of these elements are composed, water, air, vegetable, and 
animal substances. 

232. Classification of the metals. — The metals have been 
the subjects of various classifications by different writers. 
When we come to treat of them separately, we shall give 
a more practical division. In the following table they are 
arranged according to their affinity for oxygen : 



Potassium, 

Sodium, 

Lithium, 

Calcium, 

Barium, 

Strontium, 

Magnesium. 

II 
Manganese, 
Iron, 
Zinc, 
Tin, 

Cadmium, 
Cobalt, 
Nickel. 

III. 
Copper, 
Lead, 
Antimony, 
Bismuth, 
Uranium, 
Titanium, 
Cerium, 



Tellurium. 

IV. 

Arsenic, 

Molybdenum, 

Chromium, 

Vanadium, 

Tungsten, 

Columbium. 

V. 

Mercury, 

Silver, 

Gold, 

Platinum, 

Palladium, 

Rhodium, 

Osmium, 

Iridium. 

VI. 

Glucium, 

Zirconium, 

Yttrium, 

Thorinum, 

Aluminum, 

Silicium. 



Observations. — The substances in the last division have been but imper- 
fectly examined, and silicium should, perhaps, ralherbe regarded as a metal 
ioid than a metal. 

WOLLASTON'S SCALE OF CHEMICAL EQUIVALENTS. 

233. Dr. Ure says, that this scale of chemical equiva- 
lents has contributed more to facilitate the general study 
and practice of chemistry than any other invention of man. 
The description of this instrument was published by the 
inventor in 1814. It consists of a piece of mahogany board 



Describe the construction of Wollaston's scale of chemical equivalents ' 



110 CHEMICAL EQUIVALENTS. 

two or three inches wide, and of a length proportionate to 
the extent of the scale it contains, or of the size of the type 
in which it is printed. Running through the middle of the 
board there is a sliding rule containing the proportionate 
numbers of all the most common chemical compounds, and 
on each side of the rule are printed the names of the com- 
Dounds corresponding with these numbers. The divisions 
of this scale are laid out logometrically, after the manner 
of the common Gunter's scale, and consequently the ratios 
between the numbers are found by the juxtaposition of the 
several hnes on the shding and fixed parts with the great- 
est accuracy. 

234. The arrangement of this instrument is such, that the 
weight of any ingredient in a compound, or its definite pro- 
portion, and also the equivalents of the acids and alkalies, 
may be at once seen by merely moving the sliding part. 

On this scale, instead of taking hydrogen for unity. Dr. 
WoUaston has taken oxygen, which he calls 10; but if we 
slide down the middle rule so that 10 on it stands opposite 
to 10 hydrogen on the left hand, then every thing on the 
scale will be in accordance with Sir H. Davy's system of 
proportions, taking hydrogen for unity, and also in accord- 
ance with the theory of definite gaseous combination by 
volume. 

The principle on which this instrument works may be 
learned in a few minutes; and after a little practice, it 
becomes one of the most efficient and beautiful of labor- 
saving machines, to both the practical and theoretical che- 
mist. 

Nothing but actual practice with the instrument will con- 
vey to the mind of the learner a knowledge of its practical 
usefulness ; we will however give an example, by which the 
principle of its construction may perhaps be comprehended. 

235. We have already stated, that on this scale oxygen 
is the unit from which all the other proportions are calcu- 
lated, and that this element is marked 10. When, there- 
fore, 10 on the sliding rule is against this number, the weights 
of the other bodies are in due proportion to this number. 
Thus, carbonic acid being 27.54, and lime 35.46, carbonate 
of lime being the sum of these numbers, is placed at 62. 



What prinople does Dr. Wollaston call unity, and what is its number on 
the scale of chemical equivalents ? On what evidence is the truth of the 
doctrine of definite proportions founded ? 



ATOMS. 1 1 1 

Then, if the shding rule be drawn upwards, so that the 
number 100, on it, coiTesponds with carbonate of hme, the 
other numbers will correspond with carbonic acid and lime 
and will show the proportions in which these ingredients 
unite to form 100 parts of carbonate of lime. Thus, the 
number 56 corresponds with hme, while 44 corresponds 
with carbonic acid, these two numbers making 100. 

THEORY OF ATOMS. 

236. That chemical bodies unite in definite proportions, 
hy weight, and also by volume, and that where one body 
unites with another in more than one proportion, the second 
is a multiple of the first, are facts resting on the evidence of 
experiment alone. These facts, in themselves so wonderful, 
and in their relation to science so important, excited the 
inquiry and speculations of many philosophic minds, as to 
their cause. Among these inquirers, Mr. Dalton, of Man- 
chester, seems to have been the most successful, having pro- 
posed a theory which accounts, with few, if any exceptions, 
for all the phenomena observed, and which, therefore, 
explains satisfactorily the reasons why bodies combine in 
such proportions. As the basis of this theory, Mr. Dalton 
assumes that the union of bodies in their smallest propor- 
tions, always takes place between the atoms of which they 
are composed ; that is, one atom of one body combines with 
one atom of the other body. Thus, water is formed by the 
combination of one atom or particle of oxygen combined 
with one particle or atom of hydrogen. This theory sup- 
poses also that the ultimate atoms of matter are indivisible; 
that they are always of the same shape and size in the same 
body, and that their weights are different in the different 
bodies. Thus, the weight of an atom of oxygen is 8 times 
that of an atom of hydrogen, these being the proportions in 
which these gases form water. But when bodies unite in 
several proportions, then it is 2 or 3 atoms of one, to one 
atom of the other. Thus sulphurous acid is composed of 2 
atoms of oxygen united to 1 atom of sulphur, and sulphuric 
acid is composed of 1 atom of sulphur and 3 atoms of oxy- 

What is said of Mr. Dalton's theory of atoms ? What does Mr. Dalton. 
assume as the basis of his theory of atoms ? On this theory what is watei 
composed of? What does this theory suppose, in respect to the divisibility, 
shape, and weight, of the atoms of bodies ? Why is an atom of oxygen sup- 
posed to be eight times as heavy as one of hydrogen ? Why is an atom <rf 
sulphur supposed to be twice as heavy as one of oxygen ? 



1 12 ATOMS. 

gen, these being the relative weights of their elements. But 
as it is found that the lowest proportion in which sulphur 
unites with anj other body, is in the proportion of 16 bj 
weight, hydrogen being 1, so it is assumed that a particle of 
sulphur is sixteen times as heavy as one of hydrogen, and 
twice as heavy as one of oxygen. And as in sulphurous 
acid the weight of oxygen is found to be exactly double 
that in water, it is reasonable to suppose that sulphurous 
acid consists of 1 atom of sulphur united to 2 atoms of oxy- 
gen, and for the same reason, since sulphuric acid contains 
three times the weight of oxygen that water does, that this 
acid is composed of 1 atom of sulphur and 3 atoms of oxy- 
gen. 

237. All this, whether true or false, explains in the most 
satisfactory manner, why bodies combine with each other 
in definite proportions, and why these proportions are ex- 
pressed by the numbers attached to each. Thus, hydrogen 
is unity, or the prime equivalent, and is expressed by 1, be- 
cause by weight this gas is found to form water by uniting 
with 8 parts of oxygen. Oxygen is expressed by 8, be- 
cause its proportion in water weighs eight times as much 
as the hydrogen. The number for sulphur is 16, because 
this is the smallest proportion in which it unites with any 
substance, and the number for the oxygen in sulphurous 
acid is 16, because in this acid the sulphur and oxygen are 
of equal weights, and therefore just twice the weight of 
the oxygen in water; and the number for the oxygen in 
sulphuric acid is 24, because its weight is three times that 
in water. 

Now, by supposing that one atom of oxygen is 8 times 
as heavy as one of hydrogen, and that an atom of sulphur 
is twice as heavy as one of oxygen, or 16 times as heavy 
as one of hydrogen, the whole mystery of the law of defi- 
nite proportions is reduced to simple arithmetical calculation, 
for the proportional numbers are in fact nothing more than 
the relative weights of the titoms of which the several 
bodies are composed. 

238. In respect to the truth or falsity of this theory, it is 

Why is it supposed that sulphurous acid contains 1 atom of sulphur united 
to two atoms of oxygen ? That sulphuric acid is composed of 1 atom of sul- 
phur and 3 atoms of oxygen ? Why is the equivalent number of oxygen 8 ? 
Why is that for sulphur 16 ? Why is the number for oxygen in sulphuric 
acid 24? What is said of the proportionate numbers m relation to the 
weights of the atoms of bodies ? 



CHEMICAL APPARATUS. 



113 



ob\'iously ^\4thout the bounds of demonstration, for wo 
never can ascertain whether the proportions on which it lo 
founded are the smallest in which bodies combine, nor 
whether^ if so, they combine atom to atom, as is supposed, 
But whether it be true or false, it does not in the least affect 
the truth of the law of definite proportions, which, as al- 
ready stated, is founded on experiment alone, and is, there- 
fore, purely an expression of facts. The atomic theory, 
however, must always be considered an elegant and prob- 
able hypothesis ; and, while it displays uncommon inge- 
nuity^ and great chemical research, has the advantage of 
agreeing, in general, perfectly with the facts obtained by 
analysis. 

CHEMICAL APPARATUS. 

239. Before proceeding to treat of ponderable bodies, and 
the description of particular agents, it is proposed to de- 
scribe some of the most common and necessary utensils, 
used in the manipulations of chemistry. 

240. A crucible^ Fig. 35, is a deep conical cup, 
of a triangular shape at the top, and round at 
the bottom. Crucibles are made of this shape 
for the convenience of pouring out their fluid 
contents at either angle. They are made of clay 
and sand baked hard, and will withstand very 
high degrees of heat without melting, but are 
liable to crack when suddenly cooled. They are 
chiefly manufactured at Hesse, in Germany, and 
hence are called Hessian crucibles. 

241. A melting pot, Fig. 36. These pots 
aje made of various sizes and materials. Those 
used in large glass-houses are made of clay, 
and are of large size. Chemists employ those 
made of silver or platina, as well as of black 
lead, but of small dimensions. Metallic cru- 
cibles are used for particular purposes, when 
the substance to be experimented on would 
destroy the common crucible, in consequence 
of its corrosive quality. 




Fig. 36. 




What is said in respect to the truth of this theory ? Whether it is true oi 
false, does it in the leas" affect the truth of the doctrine of definite and mul- 
tiple proportions ? What is a crucible, and for what purpose is it used? Of 
what are crucibles made ? How do meltiig pots differ from crucibles ? O' 
what substances are melting pots made 1 



114 



CHEMICAL APPARATUS 



242. A matrass^ Fig. 37, is a glass vessel, in 
the snape of an egg, with a long neck. It is 
employed in effecting the solution of such sub- 
stances as require heat, and long-continued di- 
gestion, for that purpose. When used, they are 
commonly placed in a sand hath^ that is in sand 
moderately heated. 



Fig. 37 




Fig. 38. 




243. A retort and receiver 
are represented at Fig. 38. 
Retorts, a, are egg shaped 
vessels, with the neck tur- 
ned on one side. These ves- 
sels are of various capaci- 
ties, from a gill to a barrel, 

or more. They are made of 

glass, metal, or earthen ware, but most commonly of glass. 
No vessel is so much used in experimental chemistry as the 
retort. In the process of distillation, in collecting the gases, 
in concentrating the acids, and in a great variety of other 
operations, this vessel is universally employed. 

The receiver, 5, is a necessary appendage to the retort, 
and is destined to receive whatever comes over from it, 
during the process of distillation. For common purposes, 
these vessels are made of glass, but in the manufacture of 
various articles they are made of wood or metal. 

244. Fig. 39, represents a 
tubulated retort. It differs 
from the plain retort, figured 
above, in having a tubulure, or 
opening, as seen in the figure, 
to which is fitted a glass 
ground stopper. This open- 
ing saves the trouble of detach- 
ing the retort from the receiver 
when any additions are to be 
made to its contents, after they are connected, as in Fig. 
38. It is also necessary for the introduction of a safety 



Fig. 39. 




Of what are matrasses made? For what purpose are these vessels used? 
What is a retort ? How large are retorts ? Of what are retorts made ? What 
are the uses of retorts ? What is a receiver, and what is its use ? Of what 
are receivers made ? How does a tubulated, differ from a plain retort ? What 
is the use of the tubulure, or opening, in this retort ? 



CHEMICAL APPARATUS. 



115 




Fig. 41. 




tube^ a part of this apparatus absolutely necessary in some 
processes, and which will be described in another place. 

245. The alembic, Fig. 40, is used for 
the distillation or sublimation of solid, vol- 
atile substances. It consists of two parts, 
the head a, which is ground on, so as to 
be perfectly tight, and the body 6, which 
is set into a sand bath, when in use. The 
product of sublimation rises into the head, 
where it is condensed, and then runs 
down the spout into a receiver. 

246. Evaporating dish, Fig. 41. Every 
chemical apparatus must have among its 
utensils shallow dishes for evaporating flu- 
ids. The best are made of Wedgewood's 
ware, and come packed in nests containing 
several sizes each. The heat is applied by 
means of heated sand or ashes, and these 
vessels are used to evaporate solutions of 
salts, in order to obtain crystals, and for various other pur- 
poses. 

247. Fig. 42, a Florence flask, fur- 
nished with a tube, to be used instead of 
a retort. Students will save considerable 
expense by employing these flasks in the 
room of retorts. The cork is pierced 
with a burning iron, and through the ap- 
erture is passed a ti^be of glass or lead, 
bent as in the figure. In obtaining oxy- 
gen, by means of oxide of manganese and 
sulphuric acid, and for many other pur- 
poses, this arrangement will serve instead of the best retort, 
while, if broken, the expense is only a few cents. 

248. The common blow pipe, 
Fig. 43, is a httle instrument 
b}'- means of which the most vio- az 
lent heat of a furnace may be 
produced. It is a pipe of brass, 
about the third of an inch in 



Fig. 42. 




Fig. 43. 



What is an alembic ? What is the use of the alembic ? Of how many 
partjj does the alembic consist ? For what purposes are evaporating dishes 
emp..oyed ? What does Fig. 42 represent ? What are the advantages of 
using Florence flasks instead of retorts ? What is the common blow pipe 
What is the use of this instrument ? 



116 CHEMICAL APPARATUS. 

diameter at the largest end, and thence tapering, gradually, 
to a pomt, and bent, as in the figure. 

To use it, place the curved end in the flame of a lamp, or 
candle, and apply the lips to the other end, then blow 
gently and steadily, giving the jet of flame a horizontal 
direction. To keep up a constant stream of air for a length 
of time, the inspiration must be made by the nostrils, while 
the cheeks are used as bellows. The art of doing this is soon 
learned by practice. The small fragments of ore, or other 
substance, on which the flame is thrown, must be laid on a 
piece of charcoal, w^hich is held by small forceps. When 
a very intense heat is required, and the fragment is so light 
as to be blown away by the air, it may be confined by 
making a small cavity in the charcoal support, into which 
the substance is put, and another piece of charcoal is placed 
partly over this. 

249. Gakn's Blowpipe, Fig. 44, is a much Fig. 44. 
more convenient form than the common one 
above described. In the common form, the 
flame is sometimes nearly extinguished, and 
the process stopped, by the condensed mois- 
ture from the breath. In Gahn's instrument 
this is prevented by the chamber a, which 
retains the condensed moisture, and which 
may be taken off from the main pipe for its 
removal. The tip of the small pipe through 
which the air passes to the flame, fits to a 
socket, so that those of different sized orifices 
can be used. 

250. The dropping tube, Fig. 45, is a small glass 
tube, blown into a ball in the middle, and end- 
ing with a fine orifice at the lower end. It is 
filled by dipping the small end into the fluid, 
and exhausting the air hy sucking at the up- 
per *^''«d wdth the mouth. The thumb is then 
placed on the upper end, which keeps the 
liquid from running out. On raising Fig. 4.5. 

the thumb, the contents will descend 
in drops, but is instantly restrained 
replacing it. 

Describe the mode of using it? How does Gahn's blowpipe differ from 
the common one ? What are the peculiar advantages of this blowpipe ? 
Describe the construction of Gahn's blowpipe. What is the shape of the 
dropping tube ? What is the use of this insti-ument ? Describe the manner 
of using the dropping tube. For what purposes is the dropping tube useful ? 



4 



CHEMICAL APPARATUS. 



117 



This little instrument is highly useful for various 
purposes, and particularly when it is required to introduce 
one fluid under another, as water under alcohol, or sul- 
phuric acid under water. 

251. The simple arrangement, Fig. 46, is designed to 
collect and retain, for the purpose of temporary examin- 



Fig. 46. 




ation, such gases as are lighter than the 
atmosphere, and at the same time are absorba- 
ble by water. These gases, for more thorough 
examination, require the aid of a mercurial 
bath, but most of their properties may be exa- 
mined by the apparatus represented by the 
figure. 

The flask a, is to contain the materials for 
extricating the gas, and into the mouth of this 
there is inserted a tube a foot or more long. The 
tall bell glass 5, or a large tube closed at the 
upper end, is inverted over this tube, as seen in 
the figure. 

As an example of the use of this apparatus, 
suppose we desire to make some experiments 
on ammonia^ a gas which is rapidly absorbed 
by water and specifically lighter than 
atmospheric air. The materials for separating this gas are 
muriate of ammonia^ called also sal ammoniac^ and slacked 
quick-lime. These being separately reduced to powder, 
equal parts are then mixed, and introduced into the flask a, 
and the tube put into its place. On application of a gentle 
heat, the gas will be set free in consequence of the combi- 
nation which takes place between the lime and the muriatic 
acid of the muriate of ammonia. The ammonia is thus set 
at liberty, and being lighter than the air, ascends and grad- 
ually displaces the air from the vessel 5, and takes its place. 
This experiment affords an instance of the chemical action 
of two solids on each other. 

252. Gas apparatus. 
h'\g. 47 is designed as 
a simple illustration of 
a gas apparatus. The 
method of making ex- 
periments v/ith the per- 
manently elastic flu- 
ids, such as common 
air, and the gases, and 
of transferrinof them 



Fig. 47. 




118 CHEMICAL APPARATUS. 

from one vessel to another, though sufficiently simple, 
requires some directions for the new beginner. The 
gases are none of them sufficiently dense to be retained 
m vessels open to the air for any considerable time ; and 
some of them being lighter than the atmosphere, 
instantly ascend, and are lost, when the vessels containing 
them are opened. All the gases, therefore, when open to 
the air, mix with it more or less rapidly, according to their 
densities, and thus escape us entirely, being diffused in the 
atmosphere. Hence, to retain a gas in a state of puritj'-, it 
must be kept from contact with the atmosphere, and hence, 
also, the necessity of first filling the vessel with a fluid 
instead of air, before the gas is introduced, and of transfer- 
ring it under a fluid from one vessel to another. 

The figure represents a wooden vessel, or tub, a, with a 
shelf k^ k, fixed a few inches from the brim. When the 
apparatus is to be used, the tub is to be filled with water, 
so as to rise a few inches above the shelf. Now when a 
glass jar, or any other vessel, open only at one end, is filled 
with water, by being plunged into the fluid, it will retain its 
contents when raised above the fluid, provided its mouth be 
kept under it ; for the water is sustained in the vessel by the 
pressure of the atmosphere, on the same principle that the 
mercury is sustained in the barometer tube. {See Barome- 
ter in Natural Philosophy.) The vessels h. g, f. represent 
jars filled with water, and inverted on the shelf, their necks 
passing through an aperture in it, so as to preserve their 
upright positions. The vessels e, c, and z, are retorts, with 
their necks inserted into the mouths of the inverted jars. 

253. Now, when common air, or any gas, is introduced 
into the mouth of a vessel so inverted, the air will rise to the 
upper part of the vessel, and will displace the water, and 
occupy its place. If a tumbler, or cup, in the state which 
we usually call empty, but which is really full of air, be 
plunged into water with its mouth downwards, very little 
water will enter it, because the admission of the fluid is op- 
posed by the included air ; but if the mouth of the vessel be 

What is the use of the apparatus represented in Fig. 46 ? Describe Fig. 
46, and explain an example of its use. How may ammonia be obtained and 
examined by means of this apparatus ? What is represented by Fig. 47? 
W hy cannot the gas be poured from one vessel to another, and be retained 
m an open vessel like water? Explain the reason why a vessel filled with 
water may be raised above the fluid, provided its mouth be kept under it. 
When a tumbler is forced into the water with its mouth do^^■nwards, why 
does not the fluid rise in it? 



CHExMICAL APPARATUS. 



119 



turned upwards, it immediately fills with water, while the 
air is displaced, and rises to the surface of the fluid in one 
or more bubbles. Suppose this is done under the mouth of 
a jar filled with water, the air will ascend as before, but in- 
stead of escaping, it will be detained in the upper part of the 
jar. In this manner, therefore, air may be transferred from 
one vessel into another, by an inverted pouring, and the first 
portions, instead of occupying the bottom of the vessels, like 
water, ascend to the top, the air, instead of running from a 
higher to a lower vessel, rising from the lower to the higher 
one. This is owing to the pressure of the water on the air, 
or to the lightness of air when compared with water. For 
the same reason, lead being lighter than quicksilver, if a 
bullet of the former be sunk in a vessel of the latter, it will 
rise to the surface. On this principle balloons ascend ; the 
hydrogen with which they are charged being 13 times 
lighter than the atmosphere, the former is forced upwards 
by the pressure of the latter. 

254. A lamp furnace ^¥ig. 48, is 
one of the most indispensable ar- 
ticles in a chemical apparatus. It 
consists of a rod of brass, or iron, 
about half an inch in diameter, 
and three or four feet long, 
screwed to a foot of the same 
metal, or to a heavy piece of 
wood. On this rod, slide three 
or four metallic sockets, into 
which are screwed straight arms 
terminated with brass or iron 
rings of difTerent diameters. The 
screws cut on the ends of the 
arms where they enter the sockets 
are all of the same size, so that 
the rings may be changed from 
one socket to another, as con- 
venience requires. These rings 
are for the support of retorts, re- 
ceivers, evaporating dishes, &c., 
as represented in the figure, and 




When air is introduced under a vessel, inverted and filled with water, w^hy 
does it rise to the highest part of the vessel ? How does the rise of a balloon 
illustrate this principle? Describe the lamp furnace, Fig. 48. What are the 
ases of the rings on the ends of the arms ? What are the uses of the thumb 
screws with which the sockets and lamp are furnished ? 




120 CHEMICAL APPARATUS. 

may be moved up, or down, or turned aside, and then fixed in 
their places, by means of thumb screws passing through 
the sockets and acting on the rod. The lamp by which 
the heat is given for distillation, or other purposes, is also 
fixed with a thumb screw, so that the heat can be regulated 
by moving it up or down. 

255. A bell glass receiver, Fig. 49, is empi jj^ed 
in making experiments on air, or the gases. ~ 
It is a glass vessel, of the shape represented 
in the figure, and of various sizes, from the 
capacity of a pint to that of several gallons. 
The knob at the upper part, is the handle by 
which it is moved. It is used for the tempo- 
rary confinement of elastic fluids, on which 
experiments are to be made. Large tumblers 
are good substitutes for bell glasses. 

SPECIFIC GRAVITY. 

256. The specific gravity of a bodj^ is it relative weight 
when compared with the same bulk of another body. For 
solids and liquids, water is the substance to which the 
weights of other bodies are compared ; and for elastic fluids, 
the atmosphere is the standard of comparison. 

When a body weighs twice as much as the same bulk of 
water, it is said to have the specific gravity of 2 ; and if it 
weighs three, four, or five times as much as the same bulk 
of water, it has the specific gravity of 3, 4, or 5. Water, 
therefore, is the unit, or standard of comparison, and has in 
this respect the specific gravity of 1 . 

When a body is weighed in water, its weight will be 
diminished by exactly the weight of a quantity of water 
equal to its own bulk, and thus the diflerence between its 
weight in air and in water being known, its specific gravity 
is readily found. 

Taking the specific gravities of bodies is a work of con- 
siderable delicacy, and requires some practice before it can 
be done in a manner to be depended upon. The experi 
menter should always have his pencil and paper in hand, 
in order to set down the relative weights as they are taken. 



What does Fig. 49 represent? What is the use of the bell glass receiver 
What is the specific gravity of a bodj' ? With what substance are solids and 
liquids compared to find their specific gravities ? What is the standard oi 
comparison for elastic fluids ? Suppose a body weighs twice as much as the 
same bulk of v ater, what is its specific gravity ? 



CHEMICAL APPARATUS. 



121 



Fig. 50. 



f/l 



257. Portable Balance. — The most simple mode 
of taking the specific gravity of a sohd, is by 
means of NicholsorCs Portable Balance^ represented 
by Fig. 50. The body is a hollow cjdinder of 
tinned iron, terminated at each end by a cone. 
From the vertex of the upper cone rises the small 
stem, a, of copper or brass, bearing a small tin cup. 
This cup shps on, and may be removed when the 
instrument is not in use. From the point of the 
lower cone is suspended the tin cup, e, at the bot- 
tom of which is attached a cone of lead so heavy 
as to sink the whole instrument in water nearly to 
the base of the upper cone. Before this balance 
is used, it is placed in a vessel of water, and the 
upper cup loaded with weights until it sinks so far 
that a mark on the stem at a coincides exactly 
with the surface of the water. The weights, so 
added, are called the balance weights^ and their amount may 
be marked on the cup as a given quantity for future use ; 
suppose this is 900 grains. 

The specific gravity of a solid may then be taken as fol- 
lows : First place it in the upper cup, and add weights until 
the mark on the stem coincides with the water ; suppose 
this to be 400 grains ; subtract this from the balance weight, 
and we have 500 grains for its weight in air. Then remove 
the subject of experiment to the lower cup, and the stem will 
rise above the mark, because it weighs less in water than in 
air ; weights must, therefore, be placed in the upper cup 
until the mark again coincides with the surface of the water ; 
suppose this to be 100 grains, which will be exactly the 
weight of the water displaced by the mineral, or other solid. 
The specific gravity is now found by a very simple rule, 
namely, Divide the weight in air by the loss in water^ and the 
quotient will be the specific gravity. 

In the present instance, we have 500 grains for the 
weight in air, and 100 for the loss in water; therefore 
100 : : 500=: 5, the specific gravity. 

258. Specific gravity of liquids. — The most simple method 



What does Fig. 50 represent ? Describe this balance. What preparation 
is necessary before the balance is used? What are the balance weights i 
After the balance weight is known, how will you proceed to find the specific 
gravity of a body ? After finding the weight of a body in air, and its weight 
in water, what is the rule for finding its specific gravity ? What are tiie 
most simple means of finding the specific gravity of a liquid ' 

6 



122 CHEMICAL APPARATUS. 

of taKing the specific gravity of liquids, is by means of a 
graduated bottle holding 1000 grains of water, which is 
taken as the unit, or standard, for other liquids. 

Take a small bottle with a long narrow neck, 
as represented hy Fig. 51, and having weighed it Fig. 51 
accurately, introduce into it exactly 1000 grains 
of pure water, and mark the level of the water 
with a file on the neck of the bottle. The bottle 
thus prepared will serve to ascertain the specific 
gravity of any fluid, for since water is the stand- 
ard by which the comparative weights of all other 
fluids are known, the same bulk of any other fluid, 
weighed at the same temperature, will be its 
specific gravity. 

Thus, suppose that when the bottle is filled with sulphuric 
acid up to the mark at which the water weighed 1000 
grains, it should be found to weigh 1800 grains ; then the 
specific gravity of the acid would be 1800, water being 
1000. If filled to the same mark with alcohol it might 
weigh 800 grains. The specific gravity of alcohol would 
therefore be 800, v/ater being 1000. But as it is understood 
that water is the standard of comparison, the specific gravi- 
ties of bodies are expressed merely by the numbers signif^dng 
their relation to this standard. Thus the specific gravity of 
lead is 1 1, that is, it is 11 times as heavy as water, bulk for 
bulk ; while the specific gravity of ether is 750, that is, a 
given bulk of ether will weigh 750 grains, ounces, or pounds, 
while the same bulk of water weighs 1000 grains, ounces, 
or pounds. [See specific gravity i?i Natural Philosophy.) 

259. Specific gravity of gases. — To determine accurately 
the specific gravity of the gases, is an operation of great 
delicacy, and requires not only very nice apparatus, but 
much experience. The method by which it is done is, how- 
ever, easily explained, and will be readily understood. 

We have already said that atmospheric air is the stand- 
ard of comparison for the gases. In the first place, there- 
fore, it is necessary to ascertain the weight of a given 
volume of air. This is done by weighing, very accurately, 
a light glass vessel furnished with a good stop-cock, 
when full of air, or in its ordinary state. Then having with- 

I?ow does a hotrle, filled with 1000 grains of water, become the standard 
for other liquids ? Suppose a given bulk of water weighs 1000 grains, and 
tli( same bulk of another fluid 1600 grains, what would be the specific gravity 
i\ the latter Y 



CHEMICAL APPARATUS. 



123 




drawn the air, by means of an air pump, and closed the 
stop-cock, the vessel is again weighed, and the difference 
will show the weight of air which the vessel contained. On 
makii^ this experiment, it is found that 100 cubic inches of 
air weigh 30.5 grains, and bj the same method, the weight 
of a given portion of any elastic fluid may be ascertained. 
In ail these experiments, it is understood that the ther- 
mometer stands at 60 degrees, and the barometer at 30 
degrees. 

Suppose, then, that the glass globe, a. Fig. 
52, is of sufficient capacit}^ to contain 100 Fig. 52. 
cubic inches of air weighing 30.5 grains, and 
it is found, on filling it with oxygen, that the 
same quantity of this gas weighs 34 grains. 
Then to find the specific gravity of the latter 
gas we say, " as the weight of the air is to that 
of the oxygen, so is unity, or the specific 
gravity of the atmosphere to the specific gravity 
of oxygen.^' Thus, 30.5 : 34 : : 1 = 1.1147. 
gives 1 . 1 1 47 for the specific gravity of oxy- 
gen gas. 

But since it is inconvenient in practice to 
experiment on just 100 cubic inches of gas, 
the graduated vessel, 6, has been invented, 
to show at once what quantity of gas in 
cubic inches is weighed in the globe, a. 

The globe being first exhausted of air, and 
its stop-cock closed, is then connected with 
the receiver, 6, containing the gas, and both 
cocks being opened, the gas passes from the 
receiver to the globe. The receiver being 
open at the bottom, and set over water, or mercury, the rise 
of the fluid will show the quantity of gas which passes into 
the globe, and on weighing the globe, both before and aftei 
connecting it with the receiver, the difference will show the 
weight of the air thus transferred. 

260. Chemical equivalents, according to Berzelius. — Having 
inserted Brande's table of combining proportions, in v/hich, as 
there stated, (230) only whole numbers are admitted, we 




How is the specific gravity of a gas ascertained? What is the weight of 
100 cubic inches of common air? Suppose it is found that 100 cubic inches 
of oxygen gas weighs 34 grains, how is its specific gravity found ? Explain 
Fig. 52, and show the design of each vessel, and the manner of using them. 



124 



CHEMICAL EQ^'iVALENTS. 



give l)elow, also, the calculations of Berzelius and Turner, 
oji the same subject. In this it will be seen that the exact 
proportions require decimal numbers, but which we have 
avoided in this work, as being a tax on the memory, which 
the student, at least, would wish to avoid. At the same 
time, by means of this table, he can take advantage of pre- 
cise numbers, when required for any special purpose. 
" Whenever the experimental quantity," says Mr. Turner, 
"is nearly a whole number, the last maj^, for many pur- 
poses, be used as a sufficient approxiixiation ; but on all 
occasions where exact calculations are concerned, the num- 
bers given in the table should be employed." It will be 
noticed, that we have considered coiTipounds as simple mul- 
tiples of elementary whole numbers, and that, in the body of 
this work, all our calculations have been made on this prin- 
ciple. It would have been exceedingly perplexing to the 
student had we done otherwise, but the table will, of course, 
show that in nany cases this is not exactly true, though 
sufficiently near for all common purposes. 

261. Chemical equivalents of elementary substances : 



ELEMENTS. 

Aluminum . 
Antimony . 
Arsenic . . 
Barium . . 
Bismuth 
Boron . 
Bromine 
Cadmiun . 
Calcium. . 
Carbon . . 
Cerium . . 
Chlorine . 
Chromium 
Cobalt . 
Columbium 
Copper . . 
Fluorine . 
Glucinium . 
Gold . . 
Hydrogen 
Iodine . 
Iridium . 
Iron . . 
Lead . . 
Lithium . 
Magnesium 
Manganese 




I 


:at. 


IVALENTS. 

. 13.7 
. 64.6 
. 37.7 
. 68.7 
. 71 
. 10.9 
. 78.4 
. 55.8 
. 20.5 
. 6.12 
. 46 
. 35.42 
. 28 
. 29.5 
. 185 
. 31.6 
. 18.68 
. 17.7 
. 199.2 
. . 1 

. 126.3 
. . 98.8 
. . 28 
. . 103.6 
. , 6.44 
. . 12 7 
. . 27.7 



ELEMENTS. 




EQUIVALENTS 


Mercury 202 


Molybdenum . 






. 47.7 


Nickel . . . 






. 29.6 


Nitrogen 








. 14.15 


Osmium . 








. 99.7 


Oxygen . 








. 8 


Palladium 








. 53.3 


Phosphorus 








. 15.7 


Platinum 








. 99.8 


Potassium 








. 39.15 


Rhodium 








. 52.3 


Selenium 








. 39.6 


Silicium . 








. 7.5 


Silver . 








. 108 


Sodium . 








. 23.3 


Strontium 








. 43..^ 


Sulphur . 








. 16.1 


Tellurium 








. 64.2 


Thorium 








. 59.6 


Tin . . 








. 58.9 


Titanium 








. 24-3 


Tungsten 








. 94.8 


Uranium 








. 217 


Vanadium 








. 68.5 


Yttrium . 








. 32.y 


Zinc . . 








. 32.3 


Zirconium 








. 33.7 



NOMENCLATURE. 125 



NOMENCLATURE. 

262. The nomenclature of Chemistry, now universally 
employed, was invented by the French chemists about 1784. 
Before that period, the names of chemical substances were 
entirely arbitrary, that is, each substance had an inde- 
pendent name, the signification of which had nothing to do 
with its composition, or often gave an erroneous idea con- 
cerning it. Thus, solution of muriate of lime was called 
liquid shell, and afterwards oil of lime. Liquid ammonia 
was called bone spirit, and sulphuric acid was called oil of 
vitriol It is true, at that time, the substances known to 
chemists were few in number, when compared with the im- 
mense Hst of the present day. But even then, their number 
was such as to make it difficult for the memory to retain 
them, and at the same time to remember their origin or com- 
position, when this was known. At present, were the sub- 
stances mentioned in any chemical book, merely designated 
by arbitrary names, or names inexpressive of their composi- 
tion, the student would necessarily spend more time in 
learning and remembering them, than is now required to 
obtain a knowledge of the whole science of Chemistry. The 
general diffusion of chemical knowledge, therefore, is in a 
great measure owing to the present nomenclature — its per- 
fect simplicity, its copiousness of meaning, and the ease with 
which it is learned and retained. 

263. Each term designates the composition. — Each term 
in this nomenclature designates the composition of the com- 
pound substance to which it is applied ; and as the simple 
substances are comparatively few, the composition of most 
chemical substances are known only by these names. 

264. Names of the acids derived from their bases. — The 
names of the acids are derived from those of their bases, 



that is, from the names of the substances to which oxygen 
unites in such proportions as to form acids. Thus, sulphur 
is the base of sulphuric acid, and carbon is the base of car- 



When was the chemical nomenclature invented, and by whom? Before 
this invention, how were chemical substances designated? What is said 
concerning improper names before this invention ? At present, were the sub- 
stances known to chemists designated only by arbitrary names, what would 
be the consequence to the learner ? What effect has this nomenclature had 
on the diffusion of chemical knowledge ? By this nomenclature what do the 
names of the substances designate ? From what are the names of the acids 
derived? What is the base of sulphuric acid? What is the base of car- 
bonic acid ? 



1 26 NOMENCLATURE. 

oonic acid. Some of these bases unite with several pro- 
portions of oxygen, and form acids of different degrees of 
strength. These proportions are designated by the different 
terminations of the name of the acid, the smaller propor- 
tion being signified by ous^ and the larger by ic. Thus, 
sulphuroM5 and sulphur/c, and miious and nitric acids, mean 
that these acids contain single and double proportions of 
oxygen. The salts ^ that is, the compounds which the acids 
form with alkalies, earths, and metallic oxides, also indicate 
by their names the substances they contain. Thus, the 
salts ending in ite, consist of a base, united to an acid, end- 
ing in ous ; and a salt, ending in ate^ contains an acid end- 
ing in ic. Sulphzi^e and phosphzYe of potash are formed of 
potash and sulphurow^ and phosphorow^ acids, while sulph- 
ate and phosphate of potash denote compounds of sulphuric 
and phosphor2c acids, united to the same base. The names 
of all the salts, of which there are nearly 2000, denote 
their composition in the same manner, and thus we know 
the ingredients of their compositions by merely seeing their 
names. The termination uret denotes the union of simple 
non-metallic bodies with a metal, a metallic oxide, or with 
each other. Thus, sulphwre? and carburet of iron, indicate 
a combination between sulphur, or carbon, with iron. As 
oxygen combines with several of the metals, in different 
proportions, but not always sufficient in quantity to form 
acids, the compounds so formed, though derived from the 
same metal, differ from each other. These compounds are 
called oxides^ and are distinguished from each other by the 
Greek derivatives, prot, deut^ trit^ and per. Protoxide sig- 
nifies the first degree of oxidation ; tZew^oxide, the second ; 
?rz7oxide, the third ; and peroxide the highest. If it is a 
compound of one atom of acid and one of alkali, the gen- 
eric name is employed, as carbonate of potash. But if two 
or more atoms of the acid be combined with the same base, 
a numeral is prefixed to indicate its composition in this 
respect. Thus, when the acid is in two proportions, or 

By what termination in the word is a weak acid designated ? By what 
termination is the strong acid indicated? What are the compounds called 
which the acids form with different bases? If an acid ends in ow.s, what is 
the termination of the salt of which it composes a part? If the acid ends in 
ic, how does the salt end ? Hovv will you know the composition of a salt by 
merely hearing its name ? What does the termination uret denote ? What 
is thfc composition of a carhuret of sulphur? What are oxides? By what 
.erms are the different oxides denoted ? What is a deutoxide ? What is a 
trztoxide ? What is a peroxiie ? 



CHEMICAL SYMBOLS. 127 

ihere are two atoms of acid to one of potash, it is called 
^z-carbonate of potash. The three salts of oxahc acid and 
potasa are called the oxalate, iiz/oxalate, and qundrox^lRie 
of potash ; the first consisting- of one atom of each, the 
second of two atoms of acid to one of potash, and the third 
of four atoms of acid to one of potash. 

265. When oxj^gen unites in more than two proportions 
with any base, the prefix hypo is used to denote a less de- 
gree of oxj'genation than is indicated by ous. Thus, hypo- 
sulphurous acid contains less oxj^gen than sulphurous, and 
hj-posulphuric less than sulphuric. 

0x7/ denotes a dose of oxygen more than is indicated by 
ic; thus, oxychloiic acid is stronger than chloric acid. 

The terms sub, under, and super, above, are used with 
respect to the salts. When the components neutralize each 
other, it is a neutral salt : if the acid prev? .Is, it is a super- 
salt: if the alkali, it is a sub-sixli: but tlvse terms are now 
obsolete. Sesqui, one and a half, is used when elements 
combine in the proportions of one and a half to one, or as 
three to two. 

266. The following examples will show ho^v the nu- 
meral prefixes are used : 

Triphosphuret of copper 1 eq. phosphorus H-*" eq. copper 

Dinoxide of copper . 1 eq. oxygen -f''^ eq. copper. 

Subsesquiphosphuret cop. 1 eq. phosphorus +1| eq. cop. 

Protoxide of copper . 1 eq. oxygen + 1 eq. copper. 

Sesquioxide of copper . H eq. oxygen +1 eq. copper, 

Binoxide manganese . 2 eq. oxygen + 1 eq. manga. 

Teriodide of nitrogen . 3 eq. iodine + 1 eq. nitrog. 

Gluadrachloride nitrogen 4 eq. chlorine + 1 eq. nitrog. 

CHEMICAL SYMBOLS. 

267. The impracticability, in many cases, of contriving 
convenient names, expressive of the constitution of chemical 
compounds, especially of minerals, suggested the employ- 
ment of symbols, as an abbreviated mode of denoting the 
composition of bodies. It was thought, the names of ele- 
mentary substances, instead of being written at full length, 
might often be more conveniently indicated by the first 

What is said of supersalts and swftsalts ? What are carbonate and fticar- 
bonate of potash ? What is a ponderable body ? What is a simple body ? 
What is the difference between a simple and an elementary body? When 
do chemists call a body simple ? What are the uses of chemical symboxs ' 
Who invented these symbols ? 



125 



CHEMICAL SYMBOLS. 



letter of their names ; and that the combination of elements 
with each other might be expressed by placing together, in 
some way agreed on, the letters which represent them. 
The advantage of such a symbolic language was felt so 
strongly by Berzelius, that he, some years ago, contrived 
a set of symbols, consisting of the initials of the Latin 
names of the elements, which he has since used exten- 
sively in his writings ; and other eminent chemists, as well 
as mineralogists, believing symbols to be useful, adopted 
those which Berzelius had proposed. The consequence is, 
that symbolic expressions, called chemical formula^ are now 
so much resorted to, and so identified with the language of 
chemistry, that essays of great value are, in a measure, 
sealed books to those who cannot read symbols. It is, 
therefore, important, that those who are to make chemistry 
an object of science, or business, should not be unac- 
quainted with ti ese signs. The following table includes 
the symbols of all elementary bodies, according to Ber- 
zelius : 



TABLE OF SYMBOLS. 



ELBME>TS. 



SYMBOLS. 



AluminuD Al. 

Antimony v^ Stibium) . . Sb. 

Arsenic As. 

Barium Ba. 

Bismuth Bi. 

Boron B. 

Bromine Br. 



Cadmium 
Calcium 
Carbon . 
Cerium 
Chlorine 



. Cd. 

, Ca. 

. C. 

Ce. 

. CI. 



Chromium Cr. 



Cobalt 

Columbium (Tantalum) 
Copper (Cuprum) . . 

Fluorine 

Glucinium .... 
Gold (Aurum) .... 
Hydrogen . . . . 
Iodine . . .... 

Iridium 

Iron (Fermm) .... 
Lead (Plumbum) . . 
Lithium 



Manganese . 



Co. 

Ta. 

Cu. 

F. 

G. 

Au. 

H. 

L 

Ir. 

Fe. 

PI. 

L. 

M 

Mn. 



ELEMENTS. SYMBO: 

Mercury (Hydrargyrum) Hg. 
Molybdenum .... Mo 

Nickel Ni. 

Nitrogen N. 

Osmium Os. 

Oxygen O. 

Palladium ..... Pd. 

Phosphorus P. 

Platinum Pt. 

Potassium (Kalium) . . K. 

Rhodium R. 

Selenium Se. 

Siliciura Si. 

Silver (Argentum^ . . . i\g 
Sodium (Natrium) . . Na. 

Strontium Sr. 

Sulphur S. 



Tellurium Te 

Thorinum Th. 

Tin(Stannum) . . . . Sn. 

Titanium Ti. 

Tungsten (Wolfram) . . W. 

Uranium U. 

Vanadium V. 

Yttrimn Y. 

Zinc Z. 

Zirconium ... . Zr. 



CHEMICAL SYMBOLS. 129 

Sir Thomas Brancle has invented, and employs, symbols 
differing in several respects from those of Berzeiius ; so 
that those who consult his works, and those of some other 
writers, will have to learn a new series of characters, to 
signify the same elements. Those of Berzeiius are, how- 
ever, employed by most authors who have adopted the 
symbolic sj'stem of chemical writing, both in this country 
and Europe. To those students, however, who intend only 
to obtain a general knowledge of chemistry, by going once 
or twice through a manual, these signs cannot be consid- 
ered of primary importance. When formulae of considerable 
length and complexity are indicated by these signs, the 
student will, at first, find himself at a loss to comprehend 
them, and will, every moment, have to consult the table to 
understand what he sees. We have, therefore, in kindness 
to the student, thought best not to adopt them fully ; at the 
same time, giving such explanations as the subject seems 
to require, so that those who desire it can become masters 
of the whole matter. 

268. Explanation of Chemical Symbols. — These signs 
are intended to represent the chemical equivalents of the 
elements. Thus, the letters H. I. and Ba. stand for one 
equivalent of hydrogen, iodine, and barium ; and 2 H, 3 H, 
and 4 H, for 2, 3, and 4 equivalents of hydrogen. The 
formulae for compound bodies are indicated by the elements 
they contain, and the mode in which they are united. This 
may be done in several ways, but the most common method 
is, to connect together the sj^mbols by the same signs as are 
used in algebra. Thus, the formulas K4- O, Ca-f- O, Ba-f- O, 
Mn+0, Fe+O, 2 Fe + 3 O, 3 H + N, 2 H + 2 C-f 2 O, 
N + 5 O, 8 + 3 0, and H + CL, denote single equivalents of 
potassa, lime, baryta, protoxide of manganese, protoxide of 
iron, sesquioxide of iron, ammonia, olefiant gas, carbonic 
acid, nitric acid, sulphuric acid, and hydrochloric acid. 
The formula K+N-|-6 O, indicates the elements which 
are contained in an equivalent of nitrate of potassa : in 
order to express, further, that the potassium is combined 
with only one equivalent of oxygen, the remaining oxygen 
with the nitrogen, and the potassa with the nitric acid, the 
symbols are placed thus: (K+0) + (N + 5 O), the brackets 
containing the symbols of those elements which are sup- 
posed to be united. A number placed on the outside of a 
bracket multiplies the compound within it : thus (K-^0) + 
(S+3 O) is sulphate of potassa, and (K+0) + 2 (8+3 O) is 
6* 



130 J'UNDEKABLE BODIES. 

the L'jsulphate of potassa. All the elements contained in a 
compound are thus visibly represented, and the chemist is 
able readily to trace all the modes of combination, and to 
select that which is most in harmony with the facts and 
principles of his science. He may, and often does, thereby de- 
tect relations which might otherwise have escaped his notice. 
269. The above is an extract from the last edition of 
" Turner's Chemistry," and if teachers and students in this 
country adopt his opinions, the doctrine of chemical sym- 
bols will become generally understood and appreciated. 
Independently, however, of the vexation of learning such a 
number of signs, we cannot perceive the utility of employing 
them for common purposes, though already learned. Thus 
bisulphate of potash, as seen above, is thus expressed 
(KH-0)4-(2 S + 3 O.) Now, who does not see that the 
words themselves can be more quickly written than these 
signs made 1 and, w^hen printed, close attention and much 
practice is required in order to avoid errors in reading them. 



PART II. 
PONDERABLE BODIES. 

270. Explanations. — A ponderable body is one which has 
appreciable weight. 

A simple body is one which has not been decomposed. 
These are also called elements.^ or elementary bodies. 

It is possible that all the substances now called elemen- 
tary, may still be in reahty compounds, for our knowledge 
on this subject is entirely negative, that is, all bodies which 
the art of chemistry has been unable to separate into parts, 
or to decompose, are called simple^ in order to distinguish 
them from known compounds. Before the refinements of 
chemical analysis were known, it was believed that nature 
afforded only four elements, viz. fire^ air, earth, and water. 
Analysis has, however, shown, that fire, or heat, is the re- 
sult of chemical union ; that air is a compound of nitrogen 
and oxj^gen ; that there are many earths, and that water is 
composed of hydrogen and oxygen. 

How many elements were formerly supposed to exist ? What is said 
concerning fire, air, earth, and water i* 



PONDERABLE BODIES. 131 

%f I. Number of simple bodies. — The number of simple 
bodieo now enumerated amount to fifty-four. They consist 
of about 42 metals, three, or perhaps four supporters of com- 
bustion, viz. oxj^gen, chlorine, and iodine, and probably also 
bromine, and seven non-metalKc combustib.os, viz. phos- 
phorus, carbon, hydrogen, sulphur, boron, selenium, and 
nitrogen. 

Only a few years since, potash, soda, and several other 
substances, now found to be compounds, were supposed to 
be elemenictiy bodies ; and it is highly probable, that many 
substances, now arranged as simple, will soon be found to 
be compounds. 

272. Transferring the gases. — Before proceeding to de- 
scribe the properties of the gases, it might be thought 
necessary to detail more particularly than has been done, 
the modes of confining and transferring them from one 
vessel to another. But it is thought that such directions 
are better understood by the student, and much more readily 
followed when given in connexion with the particular sub- 
jects or cases to which they immmediately apply. The 
method, for instance, of transferring the nitrous oxide from 
the retort to the gasometer, and from the gasometer to the 
gas. bag, will be best understood if given in connexion with 
an account of the properties of the gas, or immediately after 
it. The same, it is thought, may be said of confining and 
transferring the other gases. As several different methods 
are required, depending on the nature of the gas, its absorp- 
tion by water, its specific gravity, and other properties, these 
different modes can be best explained and understood in 
immediate connexion with the description of the peculiar 
properties of each gas. 

273. Definite proportions. — As the doctrine of definite 
proportions is not only highly interesting as a subject of 
philosophy, but is also intimately connected with chemistry, 
both as a science, and a practical art, we shall attach to the 
name of each sulastance at the head of sections, its equiva- 
lent number, so that the reader may at once observe its 
combining proportion. And it is earnestly recommended to 
the pupil, that he should not only regard this subject as o la 



IIow many elements are now supposed to exist, and what are ther? 
What is said of the probability that some bodies now arranged as elemei ts 
will be found to be compounds? What is said rf the doctrine of defin te 
pioportions, in relation to philosophy and chemis'ry? In what other respects 
is this subject recommended to the particular attention of the pupil ? 



.32 PONDERABLE BODIES. 

of groat importance in a scientific relation, but also, when 
viewed in a different light, as one that tends directly to 
impress the mind with the most serious conviction that 
nothing in nature has been left to chance, but that the 
Almighty Creator has left a witness of Himself, even in 
the proportions and arrangement of the atoms of mattei. 
Nothing, perhaps, even the sublimest works of nature, are 
more calculated to elicit the wonder and astonishment of a 
reflecting mind, than the fact that substances combine with 
each other in exact, and definite quantities, and that these 
quantities or proportions, are the same in relation to the 
same substance throughout the world, and have been so 
ever since the creation. This discovery may be considered 
as a new proof, directed expressly to the present age, that 
the most minute works of what we call nature, do indeed 
bear the most indubitable marks of divine agency and 
design. 

274. But while the discovery itself is an evidence of the 
profound philosophy of the present age, the development 
of its principles, by the constant accession of new ideas, is 
calculated rather to humble the pride of human knowledge, 
by as constant a conviction, that after all our acquirements, 
we know comparatively nothing of tLj laws and operations 
of nature. The very fact, that the laws of proportions, 
now comparatively just known to man, have existed ever 
since the creation of matter, and have been in perpetual 
exercise all over the universe, without a suspicion of their 
existence, is of itself a sufiicient proof of the almost entire 
ignorance of man even of the phenomena of nature, and a 
still stronger proof of his ignorance of her laws. And if 
facts, in themselves so simple, yet so wonderful, and when 
once known, so obvious, have escaped the observation of 
man for thousands of years, is it not probable that phenom- 
ena are constantly going on before our eyes, which, could 
we understand them, would astonish us still more, and at 
the same time afford a still stronger conviction of our igno- 
rance, and want of penetration ? 

These considerations, while t^y are calculated to humble 
the pride of human intellect, by showing how little we 

What is said of divine agency and design m the minute works of nature? 
After all human acquirements, how much do we know of the laws and ope- 
rations of nature ? What is proved l)y the fact, that the law of definite 
Eroportions, though existing ever since the creation of matter, have, until 
itely, remained unknown ? What is said of ihe probability that wonderful 
phenomena are constantly going on before our eyes ? 



INORGANIC CHEMSITRY. 133 

know of the laws which govern even the ordinary opera- 
tions of nature, ought, by the conviction of ignorance, to 
prove an incentive to constant observation on natural phe- 
nomena, that, if possible, we might arrive at the knowledge 
of their true causes. 

INORGANIC CHEMISTRY. 

NON-METALLIC SUBSTANCES. 
OXYGEN. 

Equivalent, 8. 

275. The name oxygen is derived from two Greek words, 
and signifies the former or generator of acids, because it 
enters into the composition of most acid substances, and 
was formerly considered the universal and only acidifying 
principle in nature. 

It was discovered by Dr. Priestley, in 1774, and named 
by him dephlogisticated air. Its specific gravity is 1.11, air 
being 1. It is a non-conductor of electricity, like common 
air. Its electrical state is always negative, and when sud- 
denly and forcibly compressed, as in the fire-pump, already 
described, it emits light and heat. 

276. How obtained. — Oxygen may be obtained from many 
substances. The peroxides of lead, or manganese, and the 
nitrate and chlorate of potash, all yield it in abundance, 
when merely exposed to a dull red heat. 

The cheapest and most convenient substance for this 
purpose is black, or peroxide of manganese, in the state of 
fine powder. This, when heated in an iron bottle, or gun- 
barrel, will yield upwards of 120 cubic inches of the gas 
to an ounce of the oxide. For small experiments, a gun- 
barrel may be used ; but where considerable quantities are 
wanted, a wrought iron bottle, with a neck 18 inches long, 
is the best instrument. 



What does the term oxygen signify? Who discovered this gas ? What is the 
specific gravity of oxygen gas ? What are the substances from which it can 
be obtained ? What is the cheapest and most convenient mode of obtaining 
it ? Hov^ many cubic inches of this gas will an ounce of the black oxide of 
manganese yield ? What are the methods described of extricating this gaa 
from manganese ? 




134 OXi^GEN. 

The shape is represented at Fig. 53, with the 
adition of a piece of gun-barrel, fitted to the mouth Fig. 53 
of the bottle bj grinding. A tube, leading from 
the gun-barrel to the gas holder, conveys away 
the oxygen as it is extricated from the manga- 
nese. In the absence of such a bottle, oxygen may 
be conveniently obtained by mixing, in a proper 
vessel, one part of sulphuric acid, and two parts 
of the oxide of manganese, and applying the 
heat of a lamp. The cheapest and mosi conve- 
nient vessels for this purpose are Florence flasks, 
fitted with corks and tubes, as represented by 
Fig. 42. This and the lamp furnace, Fig 48, 
together with an inverted vessel filled with water, 
constitute the apparatus necessary for the extri- 
cation and confinement of oxygen. 

277. Theory. — With respect to the theory of these pro- 
cesses, it is necessary to state, that there are three oxides 
of manganese, each, of course, containing different propor- 
tions of oxygen. These oxides are thus constituted, the 
combining proportion of manganese being 28, and that of 
oxygen 8. 

Protoxide manganese, 28, added to oxygen, 8 = 36 
Deutoxide 28, " " 12 = 40 

Peroxide 28, " " 16 = 44. 

When the peroxide is exposed to a red heat, it parts with 
half a proportion of oxygen, that is, 4 parts, the number for 
oxygen being 8, and is therefore reduced to a deutoxide, 
whose number, it will be observed, is 40. The number for 
the peroxide being 44, and the loss by a red heat being 4, 
we obtain 4 grains of oxygen for every 44 grains of the 
oxide, which in bulk is nearly 12 cubic inches, making 
about 128 cubic inches for each ounce of the oxide. 

When oxygen is obtained by means of sulphuric acid, 
the theoretical expression is different. In this case the 
peroxide loses a whole proportion of oxygen, and is thus con- 
verted into a protoxide, which then combines with the acid, 

What apparatus is necessary for obtaining this gas from manganese by- 
means of sulphuric acid? How many oxides of manganese are there, and 
what are the proportions of oxygen in each ? What proportion of oxygen 
does the peroxide part with at a red heat ? To what oxide is the peroxide 
reduced by parting with a portion of its oxygen ? What does deutoxide mean ? 
Explain the chemical changes which take place when the oxygen is obtained 
by means of sulphuric acid. 



OXYGEN. 135 

foniiing a sulphate of manganese, which remains m the 
retort. By this process, therefore, the peroxide yields 8 
grains of oxygen to everj^ 44 grains employed ; but ni prac- 
tice it is found that the first method is the best and cheapest. 

278. It will be observed, that the weight of oxygen for 
the deutoxide, expressed above, is only 12, being a propor- 
tion and a half, instead of two proportions of that element. 
The oxides of lead and iron afford examples of precisely the 
same kind. These facts were at first supposed to afford 
exceptions to the law of definite proportions, or rather to the 
atomic theory, by which the cause of definite quantities is 
explained. But it will be remembered, as already stated, 
that the smallest proportions in which bodies have been 
found to combine, by weight, are those by which they are 
represented in numbers. Now the smallest proportion in 
which oxygen has hitherto been known to combine, is in 
water, this proportion being as 8 to 1 . The number, there 
fore for oxygen is 8. But if it should be hereafter found, in 
the course of analysis, that oxygen unites in half this pro- 
portion, in any instance, then this apparent anomaly will be 
completely explained, for then its union with hydrogen, to 
form water, will be in two proportions, and its union with 
manganese, forming the deutoxide, will be in three propor- 
tions, &c. The fact, therefore, that oxygen unites in the 
proportion of 12, is not considered a valid objection to the 
universality of the law of definite and multiple proportions, 
but only a proof that the smallest combining proportion of 
oxygen may not yet have been discovered. 

Since writing the above it has been found that a few 
bodies unite in the proportion of one and a half 

Oxygen gas is an invisible transparent fluid, like common 
air, and has neither taste nor smell. It is sparingly absorbed 
by water, 100 cubic inches of which, take up three or four 
cubic inches of the gas. 

279. Universal a.ffinity of oxygen. — Oxygen has the most 
universal affinity of any known substance, there being not 
one of the simple substances with which it may not be 
made to combine. It unites with all the metals, forming a 
very extensive class of compounds, known under the name 

What is said concerning the weight of oxygen for the deutoxide of man- 
ganese ? Why does not the discovery, that oxygen sometimes combines in 
tlie proportion of 12, tend to invalidate the atomic theory ? What is said ol 
the taste and smell of oxygen? In what proportion is this gas absorbed l>j 
water? What is said concerning the extensive affinity of oxygen? 



136 OXYGEN. 

of oxides. With some of them it combines in such propor 
lions as to form acids. Such is the case with arsenic, 
moljbdena, and others. With the simple combustibles, 
sulphur, carbon, &c., it also combines in various proportions, 
forming oxides and acids. With the metals sodium and 
potassium, it enters into combination to form the alkalies 
soda and potash. Thus the acids and alkalies, though in 
most of their properties so entirely opposed to each other, 
are composed of oxygen united to different bases, the base 
of sulphuric acid being sulphur, and that of potash being 
potassium. 

The process of oxidation sometimes takes place very 
slowly, as in the rusting of iron exposed to the atmosphere. 
In this case the affinity of the iron for the oxygen contained 
in the atmosphere, though constantly exerted, produces its 
effects very gradually, particularly if the iron is kept in a 
dry state ] but the oxidation is greatly facilitated if the iron 
is moistened with water, since, then, the metal absorbs oxy- 
gen from the water, as well as from the air. 

280. Combustion, what ? — In ordinary combustion, which 
is nothing more than a rapid oxidation, with the extrication of 
heat and light, the strong affinity between the combustible and 
the oxygen is caused by the great elevation of temperature. 
The combustible requires, in the first place, to be heated to a 
certain degree, before it will attract oxygen with sufficient 
force to emit heat and light, after which, the elevation of its 
temperature is continued by the absorption of oxygen, and 
thus the combination of one portion of oxygen with the 
burning body, causes the absorption of another. 

A combustible is any substance, capable of uniting with 
oxygen, or any other supporter of combustion, with such 
rapidity, as to cause the disengagement of heat and light. 
In this sense, iron, steel, and many other bodies, though 
they will not burn in the open air, are strictly combustibles, 
as they conform to the above definition, when heated in 
oxygen gas. 

In this gas, all combustibles burn with greatly increased 

What are the compounds of oxygen and the metals called ? Does it ever form 
acids by combining with the metals ? When combined with the metals potas- 
sium and sodium, what are formed ? What is said of the spontaneous oxida- 
tion, or rusting of iron ? What is ordinary combustion ? In combustion what 
causes the strong affinity between the buniing body and oxygen ? In kindling a 
tire, why is it necessary to raise the temperature of the wood, in order to make 
it burn ? What is a combustible body ? In what sense are iron, steel, and 
other metals, combustibles ? 



OXYGEN. 137 

splendor ; and many substances which, before the discovery 
of this gas, could not, in any sense, belong to this class, are 
now strictly combustibles. 

The combustion of various substances in oxygen gas 
affords experiments of the most briUiant and instructive kind. 

Among these, the combustion of iron, steel, and zinc, are 
highly interesting, not only becandc we are not in the habit 
of seeing metals burn, but because the first give out the most 
splendid coruscations of light, wnile the zinc burns with a 
light peculiar to itself 

281. Combustion of iron. — To exhibit the combustion of 
iron or steel in this gas, procure a piece of wire of small 
size, or what is better, a watch spring, and wind it round a 
slender rod of wood, so as to coil it in a spiral form, the turns 
of the wire being about the fourth of an inch apart. Then 
withdraw the rod, and fix to the lower end of the coil a small 
piece of thread dipped in melted bees-wax, or sulphur, or 
what is better, a little piece of spunk. The other end of the 
wire, for a few inches, is to be left straight, and fixed to the 
cork fitting the mouth of the bottle in which the experiment 
is to be made. 

Next, fill a clear glass bottle, of a quart or more capacity, 
with oxygen gas, and having set it upright, cover the mouth 
with a plate of glass, or otherwise. Then inflame the com- 
bustible on the end of the wire, and ha,ving removed the 
cover from the bottle, introduce the coil, and fix the cork in 
its place, as represented by Fig. 54. 

The wire will burn with a light too vivid 
for the eyes to bear, throwing out the most Fig. 54. 
brilliant coruscations in every direction. 
Now and then a globule of the melted metal 
will fall, and if the vessel contains water, it 
will leap on its surface for an instant or two, 
being thrown up by the steam into which it 
converts the fluid. If the vessel contains no 
water, the intense heat of the globule will 
cause it to melt the glass, and sink into its 
substance, and if the glass be thin, it will 
fuse a path quite through it, without causing 
the least fracture. 



What is said of the brilliancy of the combustion of some of the metals ? 
How IS the iron wire prepared for combustion in oxygen gas ? Describe 
Fig. 54. What causes the globules of melted iron to leap on the surface of 
the water T What is said of the action of the globules of metal on the glass ^ 




138 



OXYGEN. 



282. Combustion of zinc. — To witness the combustion of 
zinc in oxygen, first prepare the metal by mehing, and pour- 
ing it, while fluid, into the water. Then place some thin 
pieces in a spoon, prepared with a cork on its 
handle, as represented by Fig. 55, and put in the Fig. 55. 
midst of the zinc a small piece of phosphorus. 
Having a bottle of the gas prepared, as in the last 
experiment, inflame the phosphorus by holding the 
spoon over a lamp, and instantly introduce it into 
the bottle, fixing the cork in its place. The metal 
will burn with a beautiful white light, often tinged 
with green, owing to a small quantity of copper 
which the zinc contains. 

If a lighted candle be blown out, and then 
plunged into a vessel of this gas, while a spark of 
fire remains in the wick, it will be re-lighted with a slight 
explosion. 

The best way of making this experiment is, to place a 
short piece of candle in a socket, fixed to a wire, as in Fig. 
56. In this manner a candle may be blown out and again 
set on fire by dipping it into a bottle of oxygen, twenty or 
thirty times, and perhaps oftener. 

283. Changes hy combustion. — During com- Fig. 56. 
bustion in oxygen gas, the oxygen combines with Q 
the burning body, and produces remarkable 
changes, not only on the combustible, but also on 



the gas. The combustible, on examination, will 
be found to have sensibly increased in weight, by 
the combination, while the oxygen entirely loses 
the power of again supporting combustion, so that 
if a lighted candle be plunged into it, instead of 

burning with splendor, as before, it is now in- 

stantly extinguished. 

These changes are readily explained by the analysis of 
the body burned, and of the gas. The iron loses its bril- 
liancy, and is converted into a dark brittle substance, easily 
pulverised in a mortar. This is an oxide of iron, and con- 
sists of the iron itself united to the ponderable portion of the 
gas. If the iron is weighed before the combustion, and 
afterwards, it will be found to have increased in weight in 
the proportion of 8 parts to the 28. 



Describe ihe method of preparing and burning zinc in oxygen gas. What 
is the etFect when a candle is blown out, and then instantly plunged into the 
gas ? What effect does conabustion produce ou oxygen gas ? 



284. Loss of weight hy combustion. — The gas, on the con 
trary, loses in weight what is gained by the iron ; and if the 
vessel in which the experiment is made, be open at the bot- 
tom, and stand in a dish of water, the diminution of the gas 
in volmiie will be indicated by the rise of the water in the 
vessel. If the gas and iron are both accm-ately weighed before 
the experiment and afterwards, the sum of their weights 
will be found precisely the same, proving that nothing has 
escaped, and that what has been lost by the oxygen has 
been gained by the iron. When other combustibles are sub- 
mitted to the action of this gas, though they may entirely 
change their appearance by the process, or seem to be dissi- 
pated and consumed, yet nothing is lost by the burning, 
there being in all such instances merely a change of form. 
Thus, when charcoal or diamond is burned in a confined 
portion of this gas, instead of losing, as in the former exper- 
iment, the gas increases in weight, that is, it is converted 
into carbonic acid gas, by a union between the oxygen of the 
gas, and the carbon of the diamond or charcoal, so that 
what is lost by the charcoal is gained by the gas. 

In every instance the gaseous matter which remains in 
the vessel after combustion, is unfit to support animal life. 
If a bird or any other animal be confined in a limited portion 
of atmospheric air, it soon dies, because it destroys the oxy- 
gen the air contains, by converting it into carbonic acid; thus 
leaving another portion of the atmosphere called nitrogen^ 
both of which are destructive to life. {See Nitrogen.) 

If a bird be confined in a portion of oxygen, it will live 
longer than in the same quantity of atmospheric air, because 
it is the oxygen alone which supports the respiration ; but it 
dies when the oxygen is consumed, or converted into car- 
bonic acid. But if any animal be introduced into a portion 
of air after its oxygen has been destroyed, or absorbed by a 
burning body, it dies in a few seconds, unless like the frog, 
it has the power of suspending its respiration. 

What change is produced on the iron burned in it ? Why does the oxide 
of iron weigh more than the metal before it was burned ? Suppose the iron 
and oxygen are both accurately weighed before and after the experiment, what 
effect on their weights will be produced by the combustion? Is any thing 
lost by combustion? When charcoal is burned in a confined portion of oxy- 
gen gas, what effect is produced on each ? Into what gas is the oxygen con- 
verted by the process ? Will the gas left after combustion ever sustain 
animal life? Why will a bird or any other animal soon die when con- 
fined in a limited portion of common air? Why will an animal live longer in 
oxygen gas, than in the same portion ot common air ? 



140 HYDROGEN. 

285. Caution about Wells. — Finally, it is proper to 
reaiemoer, that no animal can live in an atmosphere which will 
not support combustion. 

Were this fact more generally known and remembered, 
we should not every year hear of instances where lives are 
lost by descending into old wells or cisterns. The cause of 
such accidents is the presence of carbonic acid in the bot- 
toms of such cavities ; and were the precaution taken to let 
down a burning candle, before the descent of the person, all 
danger might be avoided ; for if the flame is extinguished, 
the air will not support animal life. 

It has been recently reported, that throwing buckets of 
water in a well, where two persons had fallen down by suf- 
focation with carbonic acid gas, had been the means of 
saving their lives. {See Carbonic Acid.) 

HYDROGEN. 

Equivalent, 1. 

286. The name of this gas is derived from two Greek 
words, signifying the generator of water^ because it enters 
largely into the composition of that fluid. 

It was discovered by Mr. Cavendish in 1766. Its spe- 
cific gravity is 0.694, air being 1. — 100 cubic inches weigh 
2. 11 grains, while the same bulk of air weighs 30.5 grains; 
it is therefore about 14 times lighter than atmospheric air. 
Compared with oxygen, it is just 16 tim.es lighter than that 
gas; being indeed the lightest of all known ponderable 
bodies. It refracts hght more powerfully than any other 
body, its refraction being in the ratio of 6.6, air being 1. 
Its electricity is positive. 

287. How Obtained. — Hydrogen maybe obtained by sev- 
eral processes, but in no instance without the presence of 
water, it being evolved only by the decomposition of that 
fluid. 

The most convenient method, is to put fragments of iron 

Will an animal live in air which will not support combustion ? Will air 
which is unfit for respiration support combustion ? What precaution ought 
always to be taken before a person goes into a well or old cistern ? What is 
the derivation of the word hydrogen? What is the weight of 100 cubic inches 
of this gas? What is its weight when compared with air? How much 
lighter is hydrogen than oxygen? What substance is lighter than hydrogen 
gas? What is 'said of its power to refract light? What is the electrical 
state of this gas? Can this gas be obtained without the presence of water? 
Why? 



HYDROGEN. 



141 



or zinc into a proper vessel, and pour on them two parts by 
weight of sulphuric acid, diluted with 5 or 6 parts of water. 
The hydrogen will immediately ascend through the water 
in abundance. 

Where only small quantities 
of the gas are wanted, the sim- Fig. 57. 

pie apparatus represented at 
Fig. 57, is all that is required. 
It consists of a Florence flask 
into which the zinc and acid 
are put, with a tube leading I 




under a bell glass, or large 
tumbler fdled with water, and 
inverted in a dish of the same 
fluid. Zinc, for this purpose, 
is better than iron, and is easily 
prepared by melting, and while fluid, pouring it into water. 

The production of the hydrogen depends on the decom- 
position of the water which is effected by the united action 
of the metal and acid. The metal, having an attraction for 
oxygen, obtains it from the water; this forms an oxide of 
the metal which is instantly dissolved by the acid ; the sur 
face of the metal is thus left clean, and exposed to the water, 
from which it attracts another portion of oxygen, which is 
dissolved as before. Meanwhile, the hydrogen being thus 
detached from the oxygen, absorbs caloric, and is evolved 
in the form of hydrogen gas. 

288. Process vuth a gun barrel. — Hydrogen may also be 
obtained by passing the vapor of water through a hot iron 
tube. In this case, the oxygen of the water combines with 
the iron, while the hydrogen is set free. 

Place a gun barrel across a furnace so as to heat it red 
hot. Connect to one end of the barrel, by means of a tube, 
a retort containing water, and placed over an Argand lamp, 
and to the other end of the barrel fix a tube, leading under 
a vessel of water, inverted in a water bath. Then make the 
water in the retort boil, so that its steam may pass into the 
gun barrel, and hydrogen will be evolved, and will pass into 
the inverted vessel. 

Hydrogen, when obtained by either of these methods, is 



What is the best method of obtaining this gas ? On what does the produc- 
tion of hydrogen depend? Explain the chemical changes which take place 
during the production of this gas. By what other method may this gas be ob- 
tained ? How does the red hot gun barrel decompose the water ? 



142 HYDROGEN. 

not quite pure, but contains a little sulphur or carbon. For 
particular purposes it may be purified by passing it through 
a solution of pure potash in water. 

In this state hydrogen is without color, taste, or smell. 
It is, so far as is known, an elementary body, having resisted 
all attempts to resolve it into more simple parts. 

289. Does not support combustion. — It is inflammable, but 
not a supporter of combustion. If a lighted candle be in- 
troduced into a vessel of this gas, the flame is instantly extin- 
guished, but in passing into the gas, it inflames that portion 
which is in contact with the atmosphere. This shows that 
the combustion of hydrogen requires the aid of oxygen, 
which it absorbs from the atmosphere as a supporter. 

This experiment may be made by inverting the vesseJ 
containing the hydrogen in the open air, its levity preventing 
it from escaping downwards. In this state it will be seei? 
to burn only on the lowest surface. But if the vessel con- 
taining it be turned upright, the whole will escape in a 
volume of flame. 

290. Is used for balloons. — Hydrogen is the gas with which 
balloons are charged, and being about fourteen times lightei 
than common air, if the balloon is large, it ascends with great 
force. The principle on which balloons ascend, is the 
difference of specific gravity between the balloon as a whole, 
consisting of hydrogen, and the apparatus containing it, 
and the same bulk of atmospheric air. It is the same prin- 
ciple that makes a cork rise through water, or a leaden 
bullet through quicksilver. 

The pnnciple of balloons may be illustrated thus : Fill a 
bladder, or a gas bag, furnished with a stop-cock, with 
hydrogen gas ; attach to the stop-cock a tobacco pipe, or 
what is better, one of metal. Then dip the bowl of the pipe 
into a solution of soap, and form bubbles by pressing the 
bladder. These bubbles being detached from the pipe, will 
rise rapidly through the air. 

291. Detonates with oxygen. — When hydrogen is mixed 
with oxj^gen and inflamed, the mixture detonates violently. 
The best proportions are two parts of the hj^drogen and one 

Is hydrogen a compound or an elementary body ? "N^Tien a lighted candle 
is plunged into this gas, does it continue to burn, or is it extinguished ? Aa 
the candle passes into the gas, what part of it is set on fire ? How is this 
experiment best made ? Why does the hydrogen bum only on the surface ? 
With what gas are balloons filled? On what principle do balloons ascend? 
How may the principle of balloons be illustfSted '^ 




HYDROGEN. 143 

of oxygen hy volume. If soap bubbles of this mixture are 
touched with a candle when floating in the air, ttiey give 
a report as loud as a pistol, but much more snarp and 
stunning. 

A loud report is also given when the hydrogen is mixed 
with common air, instead of oxygen. The best proportions 
aie about three of the air to one of the hydrogen. 

This experiment may be varied by means of 
the hydrogen gun, Fig. 58. It consists of a tin Fig. 58. 
vessel, holding about a pint, the lower end being 
closed, and the upper end left open and fitted with a 
cork, a small orifice being made toward the lower 
end, as seen in the figure. 

Having filled this vessel about one third with 
water, close the small orifice with the thumb, 
and let in hydrogen till the water is displaced. 
Thus, the vessel will contain three parts of air 
and one of hydrogen. The cork being put rather 
loosely in its place, the mixture is fired by raising 
the thumb, and applying a lighted taper to the orifice. The 
cork will be driven out with violence, attended with a loud 
report. 

292. Musical tones. — When a jet of hydrogen is burned 
at the end of a tube with a fine bore, and with 
a large tube of glass, porcelain, or metal, 
musical tones are produced, which are grave or 
acute in proportion to the size or kind of tube 
employed. 

This pleasing experiment may be performed 
by placing the materials for making hydrogen 
in a convenient vessel, furnished with a tube, 
as in Fig. 59. Or the tube may be connected 
with a reservoir of gas already collected. The 
manner of holding the large tube to produce the 
musical tones is shown in the figure. 

Hydrogen cannot be breathed without dele- 
terious effects, though it is not immediately 
fatal to animal life. 




What is the consequence of firing a mixture of hydrogen and oxyo-en? 
What proportions of each make the loudest report? What are the best^ro- 
portions for mixing hydrogen and air for the same purpose ? Describe the 
method of using the hydrogen gun, Fig. 58. How are musical tones produced 
by the burnmg of hydrogen ? Explain Fig. 59. Is hydrogen a respirable gas ? 
WTiat effects does it produce when breathed ? 



144 



HYDROGEN. 



293. Action of platinum sponge on hydrogen. — The action 
of platinum sponge on hydrogen is singular and highly 
curious. When a jet of this gas is directed on a few grains 
of the sponge, both being cold, and in the open air, the 
latter immediately becomes hot, and in a moment glows 
with a red heat, setting fire to the hydrogen. 

294. Platinum sponge is prepared by dissolving the metal 
in nitro-hydrochloric acid, that is, a mixture of one part of 
nitric to 2 parts of muriatic acid. Ammonia, or muriate of 
ammonia, is added to this solution, which produces a yel- 
low precipitate. When this precipitate is exposed to a red 
heat in a crucible, the acids and ammonia are driven off, 
and there remains pure platinum, in the form of a delicate 
spongy mass. Another method of obtaining the sponge 
is, to throw the yellow precipitate on filtering paper, and 
when the liquid has passed through, to dry the paper, and 
introduce it, with the adhering precipitate, into the crucible. 

295. This curious effect of the action between platina 
sponge and hydrogen, was discovered hy Professor Dober- 
einer, of Jena, who invented the following method of pi^ 
ducing an instantaneous light by its means. 

The two vessels, a and h, 
Fig. 60, are of glass ; a is 
prolonged in the form of a 
tube, and is fitted to the 
mouth of 5, by grinding, or 
cement, so as to be air 
tight. The lower part of 
a reaches nearly to the bot- 
tom of ^, and is encom- 
passed with a strip of zinc. 
Sulphuric acid, diluted with 
five or six parts of water, 
being placed in J, a is 
fixed in its place, as seen in 
the figure. Hydrogen is 
evolved by the action of the 
acid on the zinc, and press- 
ing upon the fluid, (which 
must fill only about one 




What phenomena are produce 1 when hydrogen is tnrown in a stream upon 
platiu I sponge '' How is the platina sponge prepared? Kxpiain Fig. 60, and 
show how hydiogen is produced, and in what manner it is thrown upon the 
sponge. 



HYDROGEN. 



145 



half of b,) drives it up the tube into a. The stopper of « 
is conical, and rises to let the air from that vessel escape. 
When so much gas has been evolved as to press most of the 
acid up into «, and consequently to remove it from the zinc, 
the chemical process will cease, leaving b nearly filled with 
hydrogen. The brass tube d, is cemented to the neck c, 
and furnished with a stop-cock. The box e, contains the 
platina sponge at the end of the tube. 

When a light is wanted, nothing more is necessary than 
to open the stop-cock d, and let a jot of the gas blow upon 
the sponge, which becoming immediately red hot, a match, 
and then a candle may be lighted. By permitting the 
h3^drogen to escape, the acid again comes in contact with 
the zinc, and thus another portion of the gas is formed, and 
retained until wanted. 

296. Decomposition of Metallic Oxides by Hydrogen. — 
Many metalhc oxides when heated slightly in hydrogen gas, 
give off tbeir oxygen to form water with that gas, at the 
same time the oxide is decomposed by the loss of one of its 
components. Thus, while one compound is decomposed, 
another is forming from one of its elements, and by proceed- 
ing carefully we can detect the exact composition of each. 

Fig. 61. 




297. The apparatus, Fig. 61, is designed for this purpose. 
Ii consists of the flask a, in which the hydrogen is slowly 
generated by first introducing pieces of zinc, and then pour- 
ing through the pipe 6, sulphuric acid much diluted. In 
general a little water in the form of vapor rises with the 



Why does not the acid constantly act upon the zinc ? When one pc.*tio£ 
of the gas escapes, in what manner is another portion generated ^ 



146 WATER. 

hydrogen, for the collection of which the two bulbs c, c, are 
designed. If the gas still contains vapor, this is entirely 
withdrawn by passing through the tube d, which contains 
dry chloride of lime, a salt having a remarkable attraction 
for water. It therefore passes into the globe e, in a perfectly 
dry state. 

The ball e^ contains the metallic oxide to be decomposed, 
that of copper, for instance. After the apparatus is filled 
with hydrogen, this ball is heated by means of a spirit lamp, 
until the oxygen begins to be evolved, when uniting with 
the hydrogen, the heat thus produced keeps the copper red 
for a considerable time, thus producing a curious little self- 
acting furnace, the heat expelling the oxygen from the cop- 
per, which in its turn becomes the means of furnishing the 
heat. Before the process begins, the ball, e, is weighed 
empty, and then with its oxide of copper in it, and thus the 
weight of the copper is known. The weight of the globe g 
is also found, as well as that of the chloride of lime in the 
tube h. The water that is formed in e, passes down into g^ 
and if any vapor escape from g^ it will be absorbed by the 
chloride of potash in the tube h. At the end of the process, 
the weight of the water formed will be found by weighing 
the globe g^ with the water in it, and also weighing the 
chloride in A, and comparing the sum of these weights with 
what they weighed before. The loss of weight in e, will 
show how much oxygen was given off by the oxide of cop- 
per, and thus by estimation the bulk of oxygen can be 
known which the oxide of copper gave out. The quantity 
of hydrogen contained may also be estimated by that of the 
oxygen, the weight of this being known. Thus, the defi- 
nite proportions of the elements of water, and the composi- 
tion of an oxide may be ascertained by the same process. 

PROTOXIDE OF HYDROGEN, 9. 

1 eq. Oxygen, 8+1 eq. Hydrogen, 1. 



298. It is only necessary to remark in respect to the 
above abbreviations, that the number for water, as already 
explained, is 9, being composed of 1 proportion of oxygen 8. 
and 1 proportion of hydrogen 1. The same method being 
observed with respect to the other substances to be described, 

What is signified by the numbers affixed to water oxygen, and hydrogen 



WATER. 1 47 

ihe student has only to notice the numbers affixed to tho 
names of each substance, and he at once becomes acquainted 
with the proportions and composition of each compound, 
and the number by which the compound itself is lepresented 
This method, it is thought, will not only be found highly 
convenient, but will also greatly facilitate the acquirement 
of a proper kno^vledge of chemical equivalents ; a subject, as 
formerly remarked, of great importance to the student in the 
present state of the science. 

299. Water Produced by the Combustion of Hydrogen. — 
It has been stated that water, by analysis, is composed of 
two parts of hydrogen, and one of oxj^gen, by volume, and 
1 part hydrogen, and 8 oxygen, by weight. 

Having described the properties of these two gases sepa- 
rately, it now remains to demonstrate by synthesis.^ that is, 
by the combination of these gases, that water is the product. 

It may be seen by a very simple experiment, that when 
hydrogen is burned, water is formed. 

Fill with hydrogen a 
bladder, furnished with a Fig. 62. 

stop-cock, and small 
tube. Inflame the hy- 
drogen at the end of the 
tube, and introduce the 
flame into a dry glass 
globe with two openings, 
as represented at Fig. 62. 
As the gas burns, the 

rarefied and vitiated air will pass off at one of the openings, 
while the other admits fresh £iir to support the combustion. 
In a few minutes the inside of the globe will be covered with 
moisture, and by continuing the experiment, water will run 
down its sides, which may be tasted or otherwise examined. 
The same experiment may be made with a large glass tube 
instead of a globe. In this experiment, it is supposed that 
the combustion of the hydrogen is supported by the oxygen 
of the atmosphere, and therefore, nothing can be known of 
the proportions in which they unite. Nor would it be abso- 
hitely certain by this experiment that it was the oxygen of 

With what does the student become acquainted by observing the numbers 
affixed to names of the elements, and of their compounds ? By analysis, 
what is the composition of water, by weight and measure ? By what 
simple experiment it may be shown that when hydrogen is burned, water is 
formed ? 





148 WATER. 

tlip atmosphere which combined with the hydrogen, and 
suj'ported its combustion. 

oOO. Burned in a Close Vessel. — But when the two gases 
arc confined, each in a separate gasometer, and burned 
together in an exhausted vessel, the resuh will not only 
demonstrate to the senses that water is the product, but 
will also show the exact proportions of each element by 
weight and measure. 

For this purpose two graduated gasometers contain the 
two gases, each being furnished with a tube, leading to the 
glass globe. Fig. 63. Before the 
experiment begins, this globe is con- Fig. 63. 

nected with an air pump, by the c 

screw c, and completely exhausted ^^ 

of air, and then accurately weighed. 
It is then connected with the two 
gasometers which contain the gases 
by the pipes d and e. When every 
thing is thus prepared, the stop-cock 
d is opened, and a small stream of 
hydrogen let in, which is instantly 
inflamed by an electrical spark from 
the conductor «, this being of course 
connected with an electrical machine. The oxygen is then 
admitted, by turning the stop-cock e, and thus the combus- 
tion of the hydrogen is supported. 

At the end of the process, the graduated gasometers 
show exactly the volume of each gas consumed, and as 
the weight of 100 cubic inches of these gases is known, 
it is easy to compute the weight of the volumes consumed, 
and, by weighing the globe, to compare it with the weight 
of water produced. 

By such experiments, made with every attention to ac- 
curacy, together with that before described, of weighing 
the gases by means of exhausted vessels, Fig. 52, it is 
proved, that hydrogen and oxygen unite in the proportions 
of 2 of the first to 1 of the last, by volume ; and in the propor- 
tions of 1 and 8, by weight ; that the sole product of the corn- 
Is it absolutely certain by this experiment, that it is the oxygen of the atmos- 
phere which unites with the hydrogen to form water I How may it be demon- 
strated that the combustion of hydrogen and oxygen form water? Describe the 
apparatus represented by Fig. C3, and explain how the two gases are brought 
together, and how inflamed ? At the end of the process, how is it ascer- 
tained what proportion of each gas has been consumed, and how much water 
formed ? 



COMPOUND BLOWPIPE. 



149 



bustion of the two gases is water, and that the weight of 
the water is just equal to the combined weights of the two 
gases. In this manner has the constitution of water been 
demonstrated bejond all doubt or controversy. 



COMPOUND BLOWPIPE. 

301. When hydrogen and oxygen are burned together, 
in the proportions in which they form water, a most intense 
heat is produced. The compound blowpipe, the instrument 
by means of which the combustion of the two gases is 
regulated for this purpose, was invented by Professor Hare, 
of Philadelphia, in 1801. The apparatus consists of two 
pipes, which convey the gases from two gas-holders, to 
another short pipe, at the end of which their combustion 
takes place. 

The principle of the 
compound blow-pipe will 
be understood by Fig. 64, 
The two brass pipes, c and 
d^ are connected with the 
gas-holders, a and &, by 
coupling screws, which fix 
their lower ends to short 
tubes, furnished with stop- 
cocks, as seen in the figure. 
These stop-cocks are for 
the convenience of confin- 
ing the gas in the gas- 
holders, when the blow- 
pipe is not in use, and for other purposes connected with 
the pneumatic cistern. The two upper stop-cocks are 
designed to regulate the quantity of gas from each pipe, 
so as to produce the greatest heat, and also to stop it en- 
tirely while making experiments. 

The gas-holders, a and &, are two boxes of painted tin, 
open at the bottom, and made to fit a cistern of wood, 
about five feet long, containing water. These boxes are 
fixed in their places, at each end of the cistern, by buttons, 



Fig. 64. 



i 



What has been proved by such experiments, in respect to the quantities 
and proportions of the gases consumed, and quantity of water formed ? What 
is said of the intense heat produced by the combustion of h3'drogen and oxy- 
gen? What is the instrument called by which the combustion of the two 
gases is regulated for this purpose ? Exjilain Fig. 64, and show the uses c' 
the two tubes, the stop-cocks, and the platina tip, &c. 



150 COMPOUND BLOWPIPE. 

SO that thej cannot rise when filled with gas. They Ynixy 
be two and a half, or three feet deep, and two feet wide, oi 
of any other size, according to the extent of the experi- 
ments proposed. The cistern must be several inches 
deeper than the boxes, so that the water will rise above 
them. 

The two pipes convey the two gases separately to the 
point e, where they are soldered together, and on their 
united points is screwed a platina or silver tip, having a 
single orifice, at the end of which their combustion is ef- 
fected. If the tip is of silver, it should be large, and care 
taken not to include it in the cavity of the charcoal sup- 
port, while making experiments, otherwise it will be melted. 

Use of the Blowpipe. — Having such an apparatus 
ready, the gas-holders are put in their places, (the blowpipe 
being removed, until every thing is prepared for experi- 
ment,) and water is poured into the cistern, the stop-cocks 
being open for the escape of the air. When the cistern 
and boxes are full of water, the stop-cocks are closed, the 
blowpipe screwed on, and the two gases are conveyed un- 
der the boxes by tubes, coming from the vessels where the 
gases are evolved. One of the boxes being filled with 
hydrogen, and the other with oxygen, the blowpipe is set 
in action by turning the stop-cock connected with the hy- 
drogen, and setting the gas on fire as it issues from the tip. 
The oxygen is then admitted, when the flame of the hy- 
drogen will become less, being reduced to a sma^l blue 
flame, which gives little light, and to the eye appears in- 
significant, and totally incapable of the calorific effects 
attributed to this celebrated machine. But the student 
who has never witnessed its powers, will be struck with 
astonishment, when he finds that a piece of iron, or copper 
wire, held in this little flame, burns with nearly the same 
facility, that a cotton thread consumes in a candle ; and 
that a piece of tobacco pipe, not larger than a kernel of 
corn, will give a light, from which he will instantly be 
forced to cover his eyes. 

The compound blowpipe melts the most refractory sub- 
stances, and even dissipates in vapor those which are infusi- 
ble by the best furnaces. No means hitherto discovered, 

In filling the cistern, why are the stop-cocks left open ? What is said of 
the smallness of the flame, and the intensely heating power of this blow 
pipe ? Is there any means of producing a more intense heat than that pr<» 
duced by the compound blowpipe ? 



L 



PROPERTIES OF WATER. 151 

With the exception of the galvanic battery, produce calorific 
efiects so intense as this blowpipe. 

302. The pneumatic 
cistern above described is Fig. 65. 

represented at Fig. 65, 
with the blowpipe in its 
place. For schools, or pri- 
vate experiments, perhaps 
this is as cheap and con- 
venient a form as can 
be constructed ; since it 
serves the purpose of gaso- 
meters for the blowpipe, 
and a cistern for experiments on all the gases where a water 
bath is employed. It is believed, after having had occasion 
to direct the construction of several cisterns for the above 
named purposes, that the following dimensions are sufficient. 
Length of the cistern, 5| feet; depth, 2f or 3 feet ; width, 2 
feet ; gas-holders or boxes, 2 feet square. The cistern to be 
made of pine boards, and well painted on both sides before 
it is used. The frame and legs on which it stands must be 
separate from the cistern, about 18 inches high, and fur- 
nished with rollers. Such an apparatus, including the 
blowpipe and boxes, costs about 14 dollars. 

PROPERTIES OF WATER. 

303. It is unnecessary to describe the common properties 
of a fluid which is so universally known, that neither man 
nor animal can exist w^ithout it. The purest water, not 
having undergone distillation, is that which falls from the 
clouds. It is transparent, and without either taste or smell ; 
and being perfectly bland and neutral, it is to all animals, 
whose tastes have not been vitiated, the most agreeable of 
drinks. 

304. Weight of water. — The weight of water, as already 
shown, is the standard by which the weight or gravities of 
all solids and liquids are estimated. The weight of a cubic 
foot of pure water is 1000 avoirdupois ounces. A cubic 
inch of this fluid weighs, at the temperature of 60°, 252.52 
grains, and consists of 28.00 grains of hydrogen, and 224.46 

Explain Fig. 65. What water is purest without distillation? To what 
animals is water the most agreeable of all drinks ? What is the weight of a 
cubic foot of pure water ? What is the weight of a cubic inch of water ' 



,52 PROPERTIES OF WATER. 

grains of oxygen. By dividing 224.46 by 28.06, it may be 
seen how nearly these gases unite in the proportions of 1 and 
8 to form water. The weight of water, when compared 
with that of air, is as 828 to 1. The effect of temperature 
upon hquid water is distinguished by a pecuHarity of a very 
striking kind, and exhibits a departure from the general 
laws of nature, for a purpose so obviously wise and benefi- 
cent, as to afford one of the strongest and most impressive 
of those endless proofs of design and omniscience in the 
frame of creation, which it is the most exalted pleasure of 
the chemist, no less than of the naturalist, to trace and 
admire. 

305. Water expands in freezing. — " All liquids, except 
water, contract in volume as they cool down to their points 
of congelation ; but the point of the greatest density in water 
Is about 40'', its freezing point being 32°." As its tempera- 
ture deviates from this point, either upwards or downwards, 
its density diminishes ; or, in other words, its volume in- 
creases. This peculiar law is of much greater importance 
in the economy of nature than might at first be supposed. 
The cold air which rushes from the polar regions pro- 
gressively abstracts the heat from the great natural basins 
of water, or lakes, till the whole mass is reduced to 40° ; 
but at this point, by a wise Providence, the influence of the 
atmosphere no longer has this effect ; for the superficial 
stratum, by farther cooling, becomes specifically lighter, and 
instead of sinking to the bottom, as before, and displacing 
the warmer water, it now remains at the surface, becomes 
converted into a cake of ice, and thus preserves the water 
under it from the influence of farther cold. 

If, like mercur y-) water continued to increase in density 
to its freezing point, the cold air would continue to rob 
the mass of water of its heat, until the whole sunk to 32°, 
when it would immediately congeal into a solid mass of ice 
to the bottom, and thus every living animal it contained 
would perish. In the northern or southern temperate zones, 
such masses of ice would never again be liquefied ; a strik- 

How may it be proved that the weights of hydrogen and ox5'-gen in water 
are in the proportions of 1 to 8? What is the weight of water when com- 
paied to that of air ? At what temperature is water at its greatest density ? 
When water is above or below the temperature of 40°, how is its bulk 
affected ? In what respect is the expansion of water in freezing of great 
consequence to man ? If water, like mercury, had its density increased by 
cold to 32°, what \>ould be the consequence on large bodies of this fluid? 



OXYGENIZED WATER. 153 

ing proof of the beneficence and design of the Creator in 
forming water with such an exception to the ordinary laws 
of nature. 

306. Water contains air. — Water, in its natural state, 
always contains a quantity of air. This may be shown by 
placing it under the receiver of an air pump, for as the air 
is removed from the receiver, bubbles will be seen to rise 
from the water. The air in water is found to contani a 
larger proportion of oxygen than the common air of the 
atmosphere. The Hves of all such fishes as live entirely 
under the water, depend on the quantity of oxygen it con- 
tains, for no animal can live and move where oxygen does 
not exist. 

GASES ABSORBED BY WATER. 

307. Although water contains a considerable quantity 
of air in its natural state, amounting, according to the experi- 
ments of Mr. Dalton, to 2 cubic inches, to 100 inches of 
the fluid, it yet absorbs some of the artificial elastic fluids 
with great aviditj^, and a few of them in large quantities. 
Before exposure to the gases mentioned below, it was, how- 
ever, deprived of all aeriform matter, by long boihng. 

308. The table exhibits the quantity of each gas absorbed 
at the mean temperature and pressure of the atmosphere : 

100 VOLUMES OF 
GASES. WATER ABSORB AUTHORITY. 

VOLUMES OF 

Oxygen 3.7 Dalton. 

Chlorine 200 Gay Lussac. 

Hydrogen 1.56 Henry. 

Muriatic acid 50.000 Davy. 

Nitrogen 1.56 Henry. 

Nitrous oxide 100 Henry. 

Nitric oxide . 5 Brande. 

Ammonia 67.000 Brande. 

Sulphuric acid 3.000 Davy. 

Sulphretted hydrogen 100 Dalton. 

Carbonic acid 100 Dalton. 

Carburetted hydrogen 12.5 Gay Lussac 

DEUTOXIDE OF HYDROGEN, 17. 

2 eq. Oxygen, 16+1 eq. Hydrogen, 1. 

OXYGENIZED WATER. 

309. Water, in the scientific language of chemistry, is 
the protoxide of hydrogen ; being composed of hydrogen, 

What is said of the beneficence and design of forming water with this 
exception to the ordinary laws of nature ? How is it shown that water 
always contains air? How does the air in water differ from oomraon air'' 
7* 



154 NlTKOGi^lN. 

with one proportion of oxygen. (See Nomenclature.) It 
was supposed that hydrogen was incapable of a farther 
degree of oxj^genation, until 1818, when Thenard, a French 
chemist, showed that iDy a certain intricate process, hydro- 
gen could be made to combine with another dose of oxygen, 
and thus a new compound was formed, called deutoxide "oi 
hydrogen. 

This compound is formed in precise accordance with the 
law of definite and multiple proportions, and consists of 2 
proportions of oxygen and 1 of hydrogen, as stated at the 
head of this section. It is a highly curious and interesting 
compound. In some of its properties it exactly resembles 
water, being inodorous and colorless ; but in others, it is 
remarkably different. It is corrosive to the skin, which it 
turns white, and to the tongue it is sharp and biting, and 
leaves a peculiar metallic taste in the mouth. 

At the temperature of 58°, it is decomposed, oxygen gas 
being evolved in abundance. It is therefore necessary, in 
the summer season, to keep it surrounded with ice. It is 
also decomposed and turned into common water by nearly 
all the metals, and most rapidly by those which have the 
strongest attraction for oxygen. Some of the metallic 
oxides produce the same effect, without passing into a 
higher degree of oxidation, a fact which has not been satis- 
factorily explained. The metals, silver and platinum, in a 
state of fine division, decompose this water, when thrown 
into it, with such energy as to produce explosions. The 
same effect is produced by the oxides of silver, gold, mer- 
cury, manganese, and several other metals." 

NITROGEN. 

Equivalent, 14. 
310. This gas was formerly called a^^o^e, which signifies 
life destroyer^ because no animal can live when confined 
in it. But the same epithet might be apphed to several 
other gases, with equal propriety ; and therefore, being the 
basis of nitric acid, it is more properly called nitrogen. As 
the atmosphere is composed of four fifths of nitrogen, this gas 
may be obtained by placing a mixture of iron filings and 

What is the scientific name of water? What is deutoxide of hydro 
gen? What are the properties of oxygenized water? How does this com 
pound differ from common water ? At what temperature is this compound 
decomposed ? Why do the metals decompose this kind of water'? and what 
do they absorb from it ? What was tiie former name of nitrogen ? What 
does azote signify ? Why is it now called nitrogen ? 



ATMOSPHERE. 155 

sulphur, a little moistened, in a confined portion of air, as 
under a bell glass, over water. The mixture will absorb 
the oxj^gen from the air, and leave the nitrogen nearly pure. 
It may also be obtained by burning a piece of phosphorus 
in a vessel of air, inverted over water. The phosphorus 
forms sulphuric acid with the oxygen of the air, which 
acid is absorbed by the water, thus leaving the nitrogen 
remaining in the vessel. 

It is destructive to animal life, and is a non-supporter of 
combustion. A lighted candle plunged into it, is instantly 
extinguished, and any animal soon dies when confined in it. 
Yet it exerts no injurious influence on the lungs, the priva- 
tion of oxj^gen being the sole cause of death. 

Its specific gravity is a little less than that of atmospheric 
air, nitrogen being 0.9722, air being 1000. One hundred 
cubic inches weigh 29.7 grains. 

When combined with oxygen in certain proportions, it 
forms nitric acid. Nitrogen exists in all animal substances, 
and in such plants as putrefy with an animal odor, as cab- 
bage and raushroons. 

COMBINATION OF OXYGEN AND HYDROGEN. 

311. It has already been stated that when oxygen and 
hydrogen are burned together, the product is water. We 
have also pointed out a method of making this experiment, 
but the more simple and elegant plan of Prof Mitscherlich, 
of Berlin, is the following : 

The exact proportions in which these gases combine to 
form water, are two of hydrogen and one of oxygen, and in 
consequence of the combination, the volume is diminished 
2000 times, that is, the water takes up 2000 times less 
space than did the gases. 

In order to make this experiment with exactness, the 
gases must be quite pure. The oxygen, when obtained by 
means of chlorate of potash, is of sufficient purity; but the 
hydrogen, when evolved by means of zinc and acid, con- 
tains impurities, probably sulphurous acid gas, and must 
therefore be passed through a solution of potash, in order to 
make it fit for the experiment. 

How may nitrogen be obtained ? How is gas obtained by means of iron 
filings and sulphur? How is nitrogen obtained by means of phosphorus ? 
In what manner does nitrogen destroy life ? Is the specific gravity of nitro- 
gen greater, or less, than that of atmospheric air ? With what substance docs 
nitrogen form nitric acid ? In what vegetables is this gas found? 



156 



MISCELLANEOUS FACTS. 



i-SiS^ 




For this purpose, the simple apparatus, Fig. 66, may be 
eniptojed. Or a similar one may be readily constructed by 
means of two wide mouthed vials, bent glass tubes, and corkj*. 

This apparatus con- 
sists of the larger bot- Fig. 66. 
tie, having the cork 
pierced with two aper- 
tures for the admission 
of the two tubes, of 
which a is for the in- 
troduction of the sul- 
phuric acid, and e, f, 
for the escape of the 
;j,as. The granulated 
zinc being first placed 
in the bottle, the acid 
is poured in by the 

widened tube at b, when the gas thus produced, rises and 
passes the tube /J into the second bottle, to the bottom of 
which the tube dips, through a solution of potash. The 
gas thus rising through this solution, passes through the 
tube leading to the gasometer, in a purified state. The 
hydrogen thus purified is ready for use by means of the 
apparatus next to be described. This consists of a glass 
cistern, c, Fig. 67, for holding the 
mercury; a graduated tube, a, for Fig. 67. 

the gases ; a support to keep this 
tube from falling ; and a charged 
Ley den jar, coated inside and out, 
together with a chain as a conduc- 
tor. The tube is graduated by 
means of a small vessel, which is to 
be filled with mercury, and poured 
into it. The quantity is to be defi- 
nite, say a square inch, being the 
capacity of the cup, so that we 
know by the number of times the 
cup-full is poured in, how many 
square inches of bulk the tube con- 
tains. The tube being thus filled, 
is inverted in the mercury, as repre- 
sented in the figure. Then allowing 
the oxygen to enter at the lower end 




AND EXPERIMENTS. 157 

of the lube, its quantity is exactly ascertained by the fall of 
the mercury, as indicated by the markings on the tube, each 
mark being equal to a square inch, or a cup full of the mer- 
cury. Having admitted the oxj^gen, the hydrogen must be 
allowed to enter in small quantities at a time, to prevent 
explosion. The manner of ignition by this apparatus is 
quite simple. The tubes being pierced near the top, pieces 
of platina or iron wire are inserted, their points coming 
within striking distance, inside the tube. Then, having 
charged the vial, hold the chain in contact with the foil on 
the outside, the other end of the same being fastened to one 
of the wires which enter the tube, as seen at h. Now touch 
the other wire, c, with the brass nob, connected with the 
inside of the charged jar, and it is plain that the electric 
fluid, in passing from the positive to the negative side of the 
jar, must pass from the point of one of the wires to that of 
the other, within the tube, and thus the hydrogen is in- 
flamed, its combustion being supported by the oxygen. 

As the gases are consumed, the mercury will rise in the 
tube, showing exactly what number of cubic inches disap- 
pear, and also what quantity of water the}'" form. 

If more than twice the quantity of hydrogen, than there is 
of the oxygen, is admitted, it will remain in the tube uncon- 
sumed, and so, on the contrary, if the oxygen is more than 
half the bulk of the hydrogen, it will remain pure oxygen. 

THE ATMOSPHERE. 

312. The air which we breathe is composed of 20 parts 
of oxj^gen, and 80 parts of nitrogen, to every 100 by volume 

These proportions are found never to vary, except from 
local causes. Gay Lussac, in an aerial voyage, carried with 
him an exhausted bottle, closely corked, and when at the 
height of nearly 22,000 feet from the earth, he uncorked his 
bottle, and let in the air. It was then closely corked again, 
and brought to the earth. On examination, this air was 
found to contain precisely the same proportions of the two 
elements as that taken from the surface of the earth. Speci- 
mens of air have also been brought from Chimborazo, Mount 
Blanc, from the deserts of Africa, and from the midst of the 

Wliat is the composition of atmospheric air ? What is said of the con 
stancy of these proportions ? From what parts of the world have specimens 
of air been analysed, and found to contain the same proportions of the two 
gases? 



158 ATMOSPHERE. 

oceans, and on analysis, thej have all been found to contain 
the same proportions of the two gases. 

These proportions are found by experiment to form the 
most agreeable air for respiration, and to be best fitted foi 
the support of animal life. Animals confined in air, con- 
taining more than the ordinary proportion of oxygen, have 
their respiration hurried, and become feverish, by over ex 
citement ; while those confined to air which contains a less 
proportion of that gas, become languid and faint, from the 
want of its stimulating effects. 

313. Contains carbonic acid. — Besides these two gases, 
the atmosphere contains variable portions of carbonic acid 
gas, and aqueous vapor. The carbonic acid seems always 
to be present, since Saussure found it in the air of Mount 
Blanc, taken from the height of 16,000 feet above the level 
of the sea. Its proportion never exceeds one part in a 100, 
in freely circulating air ; and it generally amounts to only 
1,1000th or 1,2000th part of the whole. The proportion of 
aqueous vapor is also exceedingly variable, but seldom ex- 
ceeds 1 part in 100. 

The air of particular situations is also found to contain 
small quantities of carburetted hydrogen, or inflammable 
gas, and of ammonia ; but these are not constant. 

314. The atmosphere a mixture. — It has been a question 
among chemists, whether the two gases composing the 
atmosphere are simplj^ in a state of mixture, or whether they 
exist in a state of chemical combination. Mixture has com- 
monly been distinguished from combination, by the sponta- 
neous separation of the ingredients of the former. But, 
although oxygen is specifically heavier than nitrogen, no 
such instance has been found to occur. 

Air, confined in a long tube standing vertically for many 
months, was found to contain the usual proportion of oxygen 
in its upper part. The proportions of its constituents are 
also definite, like those of energetic combinations. By 
weight, there are two proportions of nitrogen 28, with 1 of 
oxygen, 8. And by volume, 4 parts of the first, 80, to one 

What is the effect of a greater proportion of oxygen than common air 
contains on the animal system ? What is the effect of a less proportion 
on the system ? Does the atmosphere contain other gases besides oxygen 
and nitrogen ? What other gas is always found in the air ? What gases ar& 
occasionall)'^ found, their presence depending on local circumstances ? What 
reasons are there to believe that air is a chemical compound ? What singulai 
fact is mentioned in respect to the mixture of carbonic acid and hydrogen 
through a tube ? 



ATMOSPHERE. 159 

of the latter, 20, in the 100, thus making the simple propor- 
tions of 4 to 1. 

It has, however; been found that other gases, of different 
specific gravities, mix with entire uniformity where it is 
known that no chemical union exists between them. Thus, 
if one vessel be filled with carbonic acid gas, and another 
with hydrogen gas, the latter being placed over the former, 
with a tube communicating between them, the two gases 
will mix with perfect uniformity in a few hours. In this 
instance, a part of the carbonic acid, though 22 times as 
heavy as the hydrogen, is found to have ascended into the 
upper vessel, while a part of the hydrogen, though 22 times 
lighter than the acid gas, descends into the lower one. The 
cause of such an intimate mixture, under such circum- 
stances, and without the influence of chemical attraction, 
has not been explained. But the fact is sufficient to show, 
that the uniform mixture of the constituents of the atmos- 
phere may be accounted for, without a chemical union. 
The facility, also, with which oxygen is abstracted from the 
atmosphere, is against a chemical union. Thus, rain water 
contains a considerable portion of oxygen, besides a portion 
of atmospheric air. But the attraction of water for oxygen 
is not supposed sufficient to overcome a chemical combina- 
tion, and therefore did such a combination exist in the atmos- 
phere, oxygen would not be found in water under such 
circumstances. 

On the whole, it is most probable, that the constituents of 
the atmosphere exist in a state of mixture, and not in a state 
of chemical union. 

315. Consumption of Oxygen . — The oxygen of the atmos- 
phere being the principle which supports life, and flame, it 
is obvious that large quantities of this gas must be consumed 
every day, and therefore that its quantity must diminish, 
unless there exists some source from which it is replaced. 
The quantity consumed, however, must be exceedingly 
small, in a definite period of time, when compared with the 
whole ; for the atmosphere not only entirely sun'ounds the 
earth, laut extends above it, at every point, about 45 miles. 
Now, when we consider how small a proportion of this 

What does this fact show with respect to the uniform mixture of the ele 
ments of the atmosphere without a chem.ical union ? What does the facihty 
with which oxygen is abstracted from the atmosphere tend to show in respect 
to this chemical union ? On the whole, is it most probable that the elements 
of the atmosphere exist in a state of mixture, or in that of a chemical union ? 



J GO NITROGEPS AND OXYGEN. 

immense mass comes into conta'ct with animals or fires at any 
one time, and that it is only these small portions that become 
vitiated, we may suppose that ages would elapse before any 
difference could be detected in the quantity of oxygen, even 
were there no means of replenishment provided. 

But the wisdom and design of Deity, which the study of 
nature every where detects, and which as constantly seems 
ordained for the benefit and comfort of man, has not loft so 
important a principle as that of vital air to be consumed, 
without a source of regeneration. 

316. Vegetation the Source of Oxygen. — It appears from 
experiments, that vegetation is the source from which the 
atmosphere is replenished with oxygen, and so far as is 
known, this is the only source. Growing plants, during the 
day, absorb carbonic acid from the atmosphere, decompose 
the gas, emit the oxygen of which it is in part composed, 
and retain the carbon to increase their growth. {See Veg- 
etation.) 

We have seen, under the article Oxygen.^ that when wood 
or carbon is burned, that oxygen is thereby converted into 
carbonic acid gas, and a greater or less proportion of this 
gas contained in the atmosphere may be attributed to this 
source. Here, then, we are able to trace another instance 
of the wonderful order and design of Omnipotence. The 
destruction of plants by burning, while the process absorbs 
the oxygen from the air, furnishes carbonic acid, which, in its 
turn, is decomposed by growing vegetables, the carbon being 
again converted into wood, while the oxygen goes to replen- 
ish the loss created by the burning, and to purify the atmos- 
phere for the use of man. 

NITROGEN AND OXYGEN. 

317. In addition to the reasons formerly assigned for sup- 
posing the atmosphere not to be a chemical compound, may 
be adduced the fact, that most other combinations of nitro- 
gen and oxygen produce corrosive or noxious substances. 



What is said of the quantity of oxygen consumed 'ly animals, and flame 
when compared with the whole, which exists in the atmosphere ? From what 
source is the atmosphere replenished with oxygen ? How do plants obtain 
the oxygen which they emit ' Whence comes the carbonic acid gas which 
plants decompose ? What is said of the wonderful order and evident design 
of Providence, in making the destruction of plants the means of replenish- 
ing the air with oxygen ? What is said of the compounds of nitrogen and 
oxygen in reference to the chemical nature of the atmosohere'' 



NITROGEN AND OXYGEN. 161 

Five such compounds are known to chemists, and tliej 
all admirably illustrate the changes produced by chemica, 
combinations, as already noticed under the article Affinity 
They also confirm the truth of the doctrine of multiple pro 
portions, having been adduced as illustrations of this prin- 
ciple under the same article. Some of the most materia^ 
properties of each of these compounds will be stated, begin- 
ning with that containing the least proportion of oxygen^ 
and endins^ with that containino^ the most. 

PROTOXIDE OF NITROGEN, 22. 

1 eq. Nitrogen, 14 x 1 eq. Oxygen, 8. 

NITROUS OXIDE. 

318. The best method of obtaining this gas is by fusing 
a salt called nitrate of ammonia. This salt may be readily 
formed by mixing carbonate of ammonia with nitric acid 
(aqua fortis) diluted with four or five parts of water, and 
then evaporating the solution by a gentle heat. The ammo- 
nia should be added in small lumps until the effervescence 
ceases ; and the evaporation continued until a drop of it, 
placed on glass, concretes. 

Having prepared the salt, the nitrous oxide, or exhilara- 
ting gas, may be procured from it, and its effects by respira- 
tion tried by the following simple means, when no better 
apparatus can be obtained. 

319. Prepare a Florence flask, as shown at Fig. 42, and 
into this put four or five ounces of the nitrate of ammonia. 
For a gas-holder, fit to a large stone-ware jug a cork 
pierced with two apertures with a burning iron ; into one of 
the apertures pass a tube of glass, or tin, so that it shall 
reach nearly to the bottom when the cork is in its place, 
and stop the other orifice with a cork. 

For a pneumatic cistern, take a common wash tub, and 
fit to it a strip of board passing through the middle, and 
about four inches from the top, so that when the tub is filled 
with water, the board will be covered. Through the board 
cut a hole to receive the neck of the jug, so that it will 
stand inverted. 



What do these compounds illustrate ? What is the signification of protox- 
ide ? What other name is there for protoxide of nitrogen ? How is this gas 
obtained ? How is nitrate of ammonia formed ? Having prepared the salt, 
in what manner is the gas extracted from it ? In what manner may a tempo- 
rary gas-holder and water bath be prepared ? 



162 JSITROGEN AND OXYGEN 

Having prepared things in this manner, fill the jug with 
water, and invert it in the tub, also previously filled with 
water. Then bend the tube belonging to the flask, so that 
it will enter the mouth of the jug, while the flask itsexf 
stands on a ring of the lamp furnace, and apply a gentle 
heat. 

If no lamp furnace is at hand, the flask may be suspended 
by a wire or string, and heated by a common lamp, or a few 
coals. The salt will soon melt and become fluid and trans- 
parent, when the gas will be extricated in abundance. 
When the jug is nearly full, which will appear by the sound 
of the bubbles, slip the hand under its mouth, and ha^dng 
set it upright, immediately put the cork, with the tube 
through it, in its place. As the nitrous oxide sometimes 
contains a mixture of nitric oxide, or hinoxide of nitrogen^ 
which is dangerous to respire, but which is absorbed by 
water, it is safest, before the gas is respired, to let it stand an 
hour or two, with the water remaining in the jug. 

To respire the gas, prepare a bladder, or oiled silk bag, 
by attaching to it a tube which fits closely to the second 
aperture in the large cork, and having squeezed all the air 
out of the bladder, or bag, remove the small cork, and pass 
in the tube. 

Next pour such a quantity of water into the jug, through 
the long tube, as it is desired to obtain gas in the bag. Now, 
the gas cannot escape through the long tube, because its 
lower end is in the water, nor can it escape through the mouth 
of the jug, this being closed by the cork ; it therefore passes 
into the bag. When this is full, withdraw the tube from 
the jug, and having expired, or thrown the air from the 
lungs, close the nose with one hand, and with the other 
apply the tube to the lips and breathe the gas from the bag 
into the lungs, and from the lungs to the bag. Sir H. Davy 
respired 12 quarts, but the medium dose is from 4 to 8 
quarts for an adult. 

320. On some persons this gas has a highly exhilarating 
or intoxicating effect, and produces the most agreeable sen- 
sations, often attended by momentary mental hallucinations, 

Having prepared the gas-holder, or jug, and the water bath, or tub, how 
will you proceed to fill the jug with gas ? How will you know w^hen the jug 
is full of gas ? What gas is sometimes mixed with the nitrous oxide ? Why 
is it safest to let the gas stand over water awhile before it is breathed I Alter 
having prepared a bladder, or gas bag, how is this filled with the gas from the 
jug ? How is the gas respired ? What is the medium dose for an aduU ^ 



^^ITRQGEN AND OXYGEN. 163 

and ooiTesponding actions. On others, it produces mental 
depression, and melancholy forebodings. Its action com 
monlj continues onlj^ for a few moments, and its effects sel- 
dom or never produce a state of languor, or debility, which 
might be expected to follow such a degree of excitement. 

The composition of the protoxide of nitrogen by volume, 
is nitrogen 100, and oxygen 50. 100 cubic inches of this 
gas weighs 46.5 grains, and its specific gravity is, therefore, 
1.5, air being 1. It is transparent, and colorless, has a 
sweetish taste, and an agreeable aromatic smell. It is a 
supporter of combustion, and many substances burn in it 
with far greater energy than in atmospheric air. The burn- 
ing body absorbs the oxygen from the nitrous oxide, and 
thus the nitrogen remains in the vessel. 

BINOXIDE OF NITROGEN, 30. 

1 eq. Nitrogen, 14+2 eq. Oxygen, 16. 

NITRIC OXIDE. NITROUS GAS. 

321. Binoxide of nitrogen, as expressed above, and as its 
name signifies, contains two proportions of oxygen to one 
of nitrogen. It was formerly called nitric oxide, and nitrous 
gas, but analysis having shown its composition, its name is 
fixed in accordance. This gas is formed by the action of 
nitric acid on copper. Having introduced some copper turn- 
ings, or filings, into a retort, pour on them a quantity of 
strong nitric acid, or aqua fortis. A violent effervescence 
will ensue, and the gas will escape in abundance. At first 
it will appear of a deep red color, which is owing to the 
presence of atmospheric air in the retort ; but on passing it 
through water the red fumes are absorbed, and the nitrous 
gas remains pure and colorless. 

322. To understand the chemical changes by which this 
gas is formed, it is necessary to state that nitric acid is com- 
posed of 40 parts of oxygen and 14 parts of nitrogen, and 
that this acid is decomposed by the process. A part of the 
oxygen of the acid unites with the copper, and forms an 
oxide of the metal, while another part of the oxygen con- 

What effect is the respiration of this gas said to produce on the human 
feelings ? What is the composition of the nitrous oxide ? What is it.s 
specific gravity? Does this gas support combustion? What does binoxide 
signify ? What is the composition, and what the equivalent numbers for bin- 
oxide of nitrogen? What was the former name of this gas? How is nitric 
oxide obtained ? Why do the first portions of this gas appear red ? What 
are the chemical changes by which this gas is formed? 



1 04 Nitrogen and oxygen. 

tinufis in union with the nitrogen, forming a binoxide of 
nitrogen, which, as ah-eadj seen, contains only 16 parts of 
oxygen. The gaseous form of the binoxide is owing to the 
absorption of a quantity of caloric at the instant of its forma- 
tion. The evolution of this gas is therefore owing to the 
abstraction of a part of the oxygen from nitric acid, by the 
copper. Other metals, and particularlj'- quicksilver, will 
produce the same effect. 

Nitrous gas, when pure, is sparingly absorbed by water. 
It is a httle heavier than atmospheric air, 100 cubic inches 
weighing 31.7 grains, while the same quantity of air weighs 
30.5 grains. It cannot be respired, even in small quantity, 
without a sense of suffocation, and violent coughing. It 
instantly extinguishes the flame of most substances, when 
plunged into it ; but if charcoal, or phosphorus, in a state of 
vivid combustion, be immersed in it, its oxygen is absorbed, 
and they burn with increased energy. 

When mixed with atmospheric air, red fumes are genera- 
ted, as already noticed. This is owing to the union of the 
oxygen of the atmosphere with the nitrous gas. When 
pure oxygen is added to a portion of this gas, the red be- 
comes still deeper, and there is formed nitrous acid, which 
is entirely absorbed by water. Thus these two gases, 
nitrous gas and oxygen, are a delicate test for each other, 
the smallest quantity of the one being detected by introdu- 
cing a quantity of the other. 

From the property of the nitrous gas above stated, it has 
been employed in Eudiometri/, that is, to ascertain the purity 
of the atmosphere, or the quantity of oxygen it contains. 

The method by which this is done, is to confine a certain 
portion of air in a graduated tube, and then to introduce into 
the tube a sufficient quantity of the gas to unite with all the 
oxygen it contains. Then, as the compound formed between 
the oxygen and the nitrous gas is entirely absorbed by 
water, it is readily seen by the graduated tube what propor- 
tion of air has disappeared, after agitating the mixture with 
water, and consequently how much oxygen it contained. 

The composition of binoxide of nitrogen has been accu- 



"WTiat causes the gaseous form of this acid ? To what is the evolution of 
this gas owing? What is the weight of this gas ? What are its effects on 
respiration and flame ? What acid is lormed wlien this gas comlnnes with 
in additional portion of oxygen gas ? By what fluid is this gas absorbed ? In 
what manner is the nitrous gas employed to ascertain the quantity of oxygen 
in the atmospheie ? 



NITROGEN AND OXYGEN. 165 

rately ascertained hy burning charcoal in it, which absorbs 
all the oxjgeii, amounting to exactly one half the volume of 
the whole, and leaves the nitrogen, which amounts to the 
other half By this analysis it is found, that 100 parts of 
this gas lose 50 parts of oxygen, and that 50 parts of nitro- 
gen remain. 

50 cubic inches of oxj^gen weigh 16.8 grains, 
50 cubic inches of nitrogen weigh 14.9 grains. 



The 100 parts, therefore, weigh 31.7 grains. 
The equivalent composition, therefore, 

is 1 atom, or equivalent of nitrogen, 14 

2 do. do. oxygen, 16 



NITR0USAC1D,46 

1 eq. Nitrogen, 14 + 4 eq. Oxygen, 32. 

323. The next compound of nitrogen and oxygen which 
we shall notice is nitrous acid. 

This acid is formed by adding oxygen to the compound 
last described, in consequence of which the nitrogen of that 
compound combines with another portion of oxygen equal to 
that which it before contained. The deutoxide contained 2 
proportionals of oxygen, 16. The nitrous acid contains 4 
proportionals of oxygen, 32. Between these, there is a 
hypothetical compound, containing 3 proportions of oxygen, 
but which has not been obtained in a free state. This is 
called hyponitrous acid^ and by some subnitrous acid, because 
it contains less oxygen than nitrous acid. 

Nitrous acid may also be obtained by the distillation of 
nitrate of lead, in a retort. {See Nitrate of Lead.) During 
the distillation, the receiver should be kept cold, by surround- 
ing it with ice. 

By either of these methods, there is obtained a vapor, or 
gas, of a deep orange red color, which is the nitric acid in 
a gaseous state. To obtain it pure, it is, however, necessary 
that the receiver should be first exhausted by the air pump, 

In what manner has the composition of this gas been ascertained ? What 
is the composition of this gas ? What is its equivalent number? What are 
the ecjuivalent numbers of its elements ? What are the processes by which 
nitrous acid may be obtained ? What is the composition of this acid ? In 
what does this acid occur, and what is its color? How is this acid obtained 
in its pure state ■? 



166 NITRIC ACID. 

because the gas is instantly absorbed by water, and a mer- 
curial bath cannot be employed, because the' gas acts upon 
that metal. 

By volimie this acid is composed of. 

Nitrogen 100 By weight, Nitrogen 14 

Oxygen 200 Oxygen 32 



300 46 

Nitrous acid, in its fuming state, is totally irrespirable j 
but supports the combustion of phosphoms, or charcoal, 
when these are introduced into it in a state of combustion. 

Water absorbs this gas in large quantities, and acquires 
thereby, first a green, and afterwards a blue tint. If still 
more be added, it becomes yellow, or colorless, and forms a 
solution of nitrous acid in water. 

NITRI C ACID, 54. 

1 eq. Nitrogen, 14+5 eq. Oxygen, 40. 

A QUA FORTIS. 

324. If a mixture of oxj^gen and nitrogen be confined in 
a glass tube containing a little water, and powerful electrical 
shocks be passed through this mixture, the water, after a 
continued succession of such shocks, will possess acid pro- 
perties. By this process, the two gases are made to com- 
bine and form nitric acid, which is absorbed by the water. 

This experiment is designed merely to prove that the acid 
in question is formed of oxygen and nitrogen. 

The usual mode of forming this acid is, by the distillation 
of the nitrate of potash, more commonly called nitre^ or 
salt-petre^ with sulphuric acid. The proportions are four 
parts of nitre, in coarse powder, with three parts of the acid 
by weight. The receiver must be large, and kept cold, 
otherwise much of the acid will escape before it is condensed. 
The strongest acid is formed when no water is placed in the 
receiver, that already combined with the sulphuric acid 

Why cannot a mercurial or water bath be employed to confine this gas ? 
What are the definite proportions of the elements of this acid by volume and 
weight 1 Does this gas support combustion or animal life ? What is said o 
its absorption by water and the colors produced thereby ? What is the com- 
position of nitric acid, and what its combining number? What experiment 
shows that this acid is formed of nitrogen and oxygen? What is the usua. 
mode of obtaining this acid ? In what manner is the strongest nitric acid 
formed ? Whence comes the water to absorb the acid vapor when none is 
placed in the receiver ? 



NITRIC ACID. 167 

being sufficient to condense the nitric acid vapor as it is 
formed. 

The strongest nitric acid is without coloi, and has a spe- 
cific gravity of 1.5, that is, this acid is by one half heavier 
than water. In this state it contains 25 per cent, of water. 

The diy nitric acid, which is formed by the condensation 
of its constituent gases, contains no water, and is composed^ 
as stated at the head of this section, of 1 proportion of nitro- 
gen, 14, and 5 proportions of oxygen, 40. The combining 
number of the dry acid is, therefore, 54. 

The acid obtained by distillation contains the same ele- 
ments as the dry acid, and in the same proportions, but with 
the addition of two proportions of water. Now, the combin- 
ing proportion of water being 9, that is, oxj^gen 8, and hy- 
drogen 1, it is easy, by the above data, to find the combin- 
ing or equivalent number for liquid nitric acid. It may be 
stated thus: 

1 eq. of Nitrogen, 14 
5 eq. of Oxygen, 40 



54 dry acid. 
2 eq. water, . . 18 



72 liquid acid. 

The acid in this state is called hydro nitric acid, from a 
Greek word signifying water, to denote its combination 
with that fluid. When this acid combines with other sub- 
stances it abandons the water, which, therefore, is not 
reckoned in its equivalent number. In this state it is called 
anhydrous nitric acid, denoting that it contains no water. 

Nitric acid is an exceedingly acrid and corrosive sub- 
stance. It stains the skin and nails of a permanent yellow, 
and is an active poison when swallowed. 

It parts with its oxygen with great facility, and hence is 
decomposed by nearly every combustible body. It com 
bines with most of the metals, and decomposes all veget- 
able and animal substances. 



What is the specific gravity of the strongest acid? What proportion ot 
water does it contain ? How is the dry nitric acid formed .' Does the acid 
obtained by distillation contain the same elements as the dry ? What are 
the constituents of liquid nitric acid ? What is the chemical name for the 
liquid nitric acid ? When this acid combines with other substances, what 
becomes of its water? What is the chemical name for the dry acid '^ What 
are the properties of nitric acid ? 



168 AMMONIA. 

As a proof of the slight degree of force with which this 
acid retains its oxygen, take some warm, dry, and fin«4y- 
powdered charcoal, and pour on it a few drachms of strong 
nitric acid. The charcoal will be ignited, with the emis- 
sion of immense volumes of red fumes. By this process 
the acid is decomposed, and parts with 2 or 3 portions of 
its oxygen to the charcoal, in consequence of which it is 
converted into nitrous acid, and deutoxide of nitrogen, 
which pass off in the form of red fumes. 

If an ounce of the spirit of turpentine be placed in a 
cup, and on it there be poured, suddenly, about half an 
ounce of this acid, the turpentine will b'? inflamed with an 
explosion, sending forth a great quantity of black smoke, and 
often throwing the acid and fire to a considerable distance. 

In both these cases, the acid parts with its oxygen with 
so much freedom, and the combustibles absorb it with such 
avidity, as to set them on fire. 

In making the latter experiment, the ^dal containing the 
acid should be tied to a long stick, othenvise the operator 
will be in danger from the explosion. 

Nitric acid forms a great number and variety of salts, 
when combined with the different metals, earths, and alka- 
lies. Most of these salts scintillate when thrown on burn- 
ing charcoal. This is in consequence of the oxygen which 
the salt emits, when exposed to heat, and by which the 
combustion of the charcoal is rendered more vivid. This 
scintillation is a sure proof that the salt is a nitrate. 

All the nitrates are soluble in water, and many of them 
furnish oxygen gas, of more or less purity, when heated in 
a retort. 

NITROGEN AND HYDROGEN. 

AMMONIA, 17. 

I eq. Nitrogen, 14-|-3 eq. Hj^drogen, 3. 

HARTSHORN. 

325. There is a substance well known to arti?ts, and 
others, by the name of sal-ammoniac. In chemistry its 

How is it shown that, this acid holds its oxygen with a slight force? What 
effect does the action of the charcoal have on this acid ? What are the red 
fumes which pass off during this experiment? How may spirit of turpen- 
tine be inflamed by this acid ? Why are the combustibles set on fire by this 
acid ? What is said of the salts formed bj' the combinations of nitric acid ? 
Why do the salts of this acid scintillate when thrown on burning charcoal ? 
What is said of the solubility of the nitrates ? How is ammonia obtained ? 



AMMONIA. I6q 

name is muriate of ammonia. If some of this substance bo 
pulverized b}^ itself, and then mixed with an equal portion 
of unslacked quicklime, also in powder, and then intro- 
duced into a retort ; upon the application of a gentle heat, 
there will arise an extremely pungent gas, which is am- 
monia. 

Water absorbs this gas with great avidity, and in large 
quantities, and consequently it cannot be collected like 
most other gases, by means of the water bath. 

In the absence of a mercurial bath, therefore, its proper- 
ties can be examined by receiving it in a bladder attached 
to the retort, or by means of a tall bell glass, and the appa- 
ratus described at Fig. 49. This gas is transparent, and 
colorless. In its pure state it cannot be respired. An ani- 
mal cannot live in it, and it extinguishes the flame of burn- 
ing bodies. 

This gas is composed of 

1 equivalent, or atom of nitrogen, 1 4 
3 do. do. hydrogen, 3 

Its combining weight is, therefore, 17 

It is much lighter than atmospheric air, 100 cubic inches 
weighing only 18 grains. 

When this gas is absorbed by water, which will take up 
more than 500 times its own bulk of it, there is formed the 
well known pungent liquid called spirit of sal ammoniac.^ or 
spirit of hartshorn.^ and by the apothecaries, liquid ammonia. 

When ammoniacal gas is submitted to the pressure of 6 
or 7 atmospheres, equal in the whole to about 100 or 120 
pounds to the square inch, it is condensed into a clear color- 
less liquid, but when the pressure is removed, it again ex- 
pands, and assumes its former gaseous state. 

Ammonia is called the volatile alkali, by which it is dis- 
tinguished from the fixed alkalies, soda and potash. It 
possesses, fully, all the properties of an alkaU, having an 
acrid taste, a strong affinity for water, and being capable f 
neutralizing the corrosive qualities of the acid.j. 

Wliy cannot this gas be collected under water ? How may its properties 
be examined without a mercurial bath ? What are the most obvious proper- 
ties of ammonia? What is the composition of ammonia, and what is its 
equivalent number? What is the weight of 100 cubic inches of this gas ? 
How is liquid ammonia formed? What quantity of this gas will water 
bsorb ? What is said of the condensation of ammonia into a liquid? 

8 



1 7Q CARBON. 

The article used in smelling bottles, and called volatile 
salts, and salt of hartshorn, is a carbonate of ammonia. 

The salts of ammonia, and particularly the muriate and 
carbonate, are articles of considerable importance in com- 
mercCj in the arts, and in medicine. 



Equivalent, 6, 

326. Nature furnishes carbon in its purest state in the 
form of that precious gem, the diamond. 

That the diamond is nothing but pure carbon, is proved 
by direct analysis. If in a glass vessel containing oxygen 
gas, a piece of diamond be placed, and then exposed to the 
intense heat of a large convex lens, or burning glass, the 
diamond entirely disappears, and there remains in the vessel 
carbonic acid, instead of oxygen. Thus the diamond, like 
other combustibles, forms carbonic acid by being burned, or 
by uniting with oxygen. When charcoal, or carbon from 
wood, is burned in pure oxygen gas, exactly the same re- 
sult is produced, the charcoal entirely disappears, and the . 
oxygen is converted into carbonic acid. 

Charcoal may be obtained for experiments, by burying 
wood under sand, in a crucible, and exposing it to an intense 
heat for an hour or two. ^y this process, the water and 
other ingredients of v/hich wood is composed are driven off, 
and the carbon remains, 

327. Both diamond and charcoal sustain the most intense 
degrees of heat, without change, provided oxygen is entirely 
excluded from them. Charcoal, when newly prepared, pos- 
sesses the property of absorbing large quantities of air, or 
other gases, at common temperatures, and of yielding the 
greater part of them again when heated. There is, how- 
ever, a great difference in respect to the quantity absorbed, 
dep^ nding on the kind of gas with which the experiment is 
w Ae. Ammoniacal gas is taken up in the largest quantity, 
inis being 90 times the bulk of the charcoal. Muriatic acid 
gas is absorbed in the proportion of 85 times the bulk of the 

What is the article called volatile salts? What is said of the alkaline pro- 
perties of ammonia ? How is it proved that the diamond is composed of pure 
carbon? When diamond, or charcoal, is burned in oxygen gas, what is the 
product ? How may charcoal be obtained from wood in a pure state ? What 
peculiar property does newly prepared charcoal possess ? What difference 
is there in respect to the quantity of the different gases absorbed by charcoaJ f 



CARBON AND OXYGEN. 17 1 

charcoal. Other gases are absorbed only m small propor- 
tions, nitrogen being only 7| times, and hydrogen 1.75 tunes 
the bulk of the charcoal. The greatest .absorption takes 
place in charcoal made from the most compact kinds of 
wood, and the amount is much diminished when the char- 
coal is reduced to powder. Charcoal, recently prepared, 
has the property of resisting putrefaction in animal sub- 
stances, and of rendering such substances sweet, after they 
are tainted. The most offensive stagnant water loses its 
odor and becomes perfectly sweet by being filtered through 
powdered charcoal. 

It also destroys the color of many substances. Vinegar 
loses its color, and becomes transparent like water, by being 
boiled with charcoal ; and red wines, or colored brandy, are 
bleached by passing through it. The best charcoal for these 
purposes is prepared by calcining animal substances in 
close vessels. 

In the present state of knowledge, charcoal is a simple 
substance, having resisted all attempts to decompose, or sep- 
arate it into other elements. Its atomic weight or combin- 
ing number is 6, this being the proportion in which it is found 
to unite with oxj^gen, to form carbonic acid; and in no 
instance has it been detected in a less proportion in combi- 
nation. 

CARBON AND OXYGEN. 

CAR.BONIC ACID, 22. 

1 eq. Carbon, 6+2 eq. Oxygen, 16. 

FIXED AIR. 

328. It has just been stated, that when diamond or char- 
coal is burned in oxygen, the latter is changed into carbonic 
acid. By this process the volume of oxygen is not changed, 
but its weight is increased by exactly the amount of the 
diamond, or charcoal, consumed. Carbonic acid, therefore, 
consists of oxygen, with a quantity of charcoal dissolved 
in, or combined with it. 

What gases are absorbed in the greatest, and what in the least quantity ? 
What effect does newly prepared charcoal have on putrefying animal sub- 
stances? What effect does charcoal have on the color of particular sub- 
stances? What kind of charcsal is best for the above purposes? Is char- 
coal a simple, or a compound body? What is the combining number, or atomic 
weight, of carbon? When diamond, or charcoal, is burned in a confined por- 
tion of oxygen gas, what effect does the combustion have on the volume and 
weight of the gas ? 



17-2 



CA.RBON AND OXYGEN. 



'J 'his acid can. however, be obtained bj a much cheaper, 
ana more direct method, than by the combustion of diamond, 
or even of charcoal, in oxygen gas. 

Carbonic acid exists in a fixed state, in vast abundance, 
as a part of the composition of hmestone or marble. This 
chemical compound, so abundant in nature as to form im- 
mense mountains, is composed of 22 parts of carbonic acid, 
and 28 of hme. 

329. Preparation of Carbonic Acid. — Carbonic acid may 
therefore, be obtained most readily, by exposing carbonate 
of lime to the action of some acid which has a stronger 
affinity to the lime than the acid has with which it is nat- 
urally combined, and thus by forming a new compound 
between the lime and the stronger acid, the carbonic acid 
will be set at liberty. 

Fig. 68. 




For this purpose introduce pure white marble, in small 
fragments, into the two necked bottle «, Fig. 58, having the 
bent tube c, connected with one of the necks, and passing 
under the jar <Z, filled with water and inverted in the water 
bath. Then pour through the funnel Z>, some sulphuric acid, 



In what natural compound is carbonic acid contained in great abundance? 
What proportion of carbonic acid does marble contain ? What are the che- 
mical principles on which carbonic acid may be obtained from limestone, or 
marble ? Explain Fig. 58, and describe the process of obtaining carbonio 
acid gas from marble 1 



CARBON AND OXYGEN. 173 

diluted with five or six parts of water. Effervescence will 
immediately ensue, in consequence of the escape of the gas, 
which in a few minutes will be seen to rise in bubbles 
through the water in the jar. 

The chemical changes during this process illustrate the 
law of simple affinity, formerly explained, viz., that one sub- 
stance may have an attraction for several others, but with 
different degrees of force. Thus lime has an affinity for car- 
bonic acid, with which it combines and forms carbonate of 
lime. But sulphuric acid having a still stronger attraction 
for the lime, when this is added, the carbonate is decom- 
posed, the sulphuric acid and lime unite and form sulphate 
of lime, while the carbonic acid being thus rejected, escapes 
in the form of gas. 

330. Properties of Carbonic Acid. — This gas is inodor- 
ous, colorless, and elastic. It extinguishes burning substan- 
ces of all kinds, and is so poisonous that a small quantity 
of it mixed with atmospheric air destroys animal life. 

It is this gas which destroys the lives of many persons 
every winter, in consequence of warming close rooms with 
open vessels of burning charcoal. In such cases the air 
becomes noxious from two causes ; the charcoal, by abstract- 
ing the oxygen from the atmosphere, would leave only the 
nitrogen, which, as we have already seen, will not support 
animal life. The mere absence of the oxygen would, there- 
fore, be the negative means of destroying life. But this is 
not the most active cause of destruction. The air is not 
only deprived of its oxygen, by the burning charcoal, but 
the oxygen, by uniting with the charcoal, becomes an abso- 
lute poison ; this is indeed of so deleterious a nature, that 
when pure, it causes death by producing a spasm of the 
glottis, thus closing entirely the passage to the lungs, and 
when mixed with atmospheric air, in such a proportion as to 
be taken into the lungs, it then acts as a narcotic poison, 
producing dimness of sight, loss of strength, difficulty of 
breathing, then entire suspension of respiration, and finally, 
insensibility, apoplexy, and death. 

331. When limestone is exposed to heat, this gas is 



Explain how this process illustrates the law of simple affinity. What new 
salt is formed when sulphuric acid is poured on marble ? What is the effec 
of this gas on flame, and animal life ? When charcoal is burned in an open 
vessel, in a close room, what is the effect on the air of the room ? How does 
pure carbonic acid cause death ? When mixed with air, so as to be respired 
how does it cause death ? 



174 CARBON AND OXYGEN. 

driven off, and in consequence of this loss, the limestone is 
converted into quick lime, a substance well known as the 
basis of mortar for building. The gas, thus extricated, 
being quite pure, is exceedingly deleterious, and sometimes 
proves fatal to the workmen and others in the vicinity of 
the kiln, where the burning is performed. 

332. Family destroyed iy carbonic acid. — M. Foder states, 
that in the year 1806, a family residing at Marseilles, con- 
sisting of seven persons, were all rendered apoplectic, 
in consequence of breathing carbonic acid, which was 
extricated from an oven in the yard of the house, where 
limestone was burning. The gas had come into the house 
through the door and windows, and by some means it was 
found, during the night, that the family were in danger, 
and the alarm was given, but not in time for any one to 
escape. In the morning all the seven were found in different 
places, one on the stairs, one on the step of the door, &c., 
with lamps in their hands, in the attitude of flight ; but the 
deleterious gas had taken away their strength, and put out 
their lights. They all appeared to have fallen down of 
apoplexy, while attempting to escape death by flight. Five 
were dead beyond recovery, but the two others were brought 
to life. 

Some people, who are perfectly aware of the poisonous 
eflects of the air arising from ignited charcoal, which has 
been prepared in coal-pits, still unaccountably believe, that 
the coals from a common fire are innocent. This opinion 
has probably arisen from the circumstance, that coals from 
the fire are taken up with a quantity of ashes, in which they 
are chiefly covered, so that their combustion is made less 
rapid than when charcoal alone is used. But that there is 
no difference in respect to the poisonous property of this 
gas, whether the charcoal has been prepared in a coal pit, 
or on the hearth, is proved by the fact, that a respectable 
citizen and his wife, a short time since, had nearly fallen 
victims to this mistaken opinion. 

333. Water absorbs this gas. — Water absorbs carbonic 
acid from, the atmosphere, and it is owing to its presence in 
spring and well water, that we are indebted to their pleasant 

When limestone is exposed to a red heat, what changes are produced on 
it ? What were the circumstances under which a family at Marseilles were 
rendered apoplectic by this gas ? Is there any difference between the pois- 
onous effects of charcoal prepared in a coal pit, and that taken from the 
nearth? What is said of the absorption of this gas by water, and the lively 
taste given the fluici in c jnsequence ? 



CARBON AND OXYGEN. 175 

flavor. Boiling causes this gas to escape in consequence 
of the heat, and whoever has tasted of water immediately 
from a fountain, and of another portion of the same water, 
which has been boiled, will observe a remarkable difference. 
Water which has been recently boiled, will absorb its own 
bulk of carbonic acid, when agitated with it. The smart 
and agreeable taste peculiar to soda water, to lively beer, 
champaigne, cider, and porter, is owing to the presence of 
this gas. This shows that, though a deadly poison when 
taken into the lungs, it may be taken into the stomach, not 
only with impunitj'', but with pleasuse. 

334. The poisonous quality of this gas is a striking in- 
stance of the change produced on bodies by chemical com- 
bination. Charcoal alone is so inert as to be taken into the 
stomach in any quantity, without other deleterious effects 
than what might arise from over distention ; and in fine 
powder it is so far from being injurious to the lungs, that 
the coalmen consider their business as of the most healthy 
kind. Oxygen, as it exists in the atmosphere, is the very 
pabulum of animal life, and when perfectly pure, may be 
respired without any other ill effects, except what arise from 
over excitement. But when these two substance^! are chemi- 
cally united, they form, as already described, a compound 
of the most deleterious kind, a poison which, according to 
M. Halle, destroys animal life in the space of two minutes. 

The specific gravity of this gas is 1 .52, air being 1 ; so 
that it is about one half heavier than air. It may be poured 
from one vessel to another, like water ; and as it instantly 
extinguishes flame, lights may be put out with it in a 
manner which will puzzle and astonish those who are not 
in the secret. If a short piece of candle be lighted and set 
in a tumbler, and then a jar of this gas, which in appear- 
ance contains nothing, be held so that its contents run into 
the tumbler, the hght will be as effectually extinguished as 
though the tumbler had been filled with so much water. 

335. Test of carbonic acid. — One of the best tests of the 
presence of this acid is lime water, which though perfectly 
transparent before, instantly becomes cloudy or turbid, when 

Why does water which has been boiled taste flat and insipid? To what 
liquids does this gas give their smart and lively taste ? What does this prove 
in respect to the poisonous quality of this gas ? How do the poisonous quali- 
ties of this gas illustrate the changes produced on bodies by chemical combi- 
nations? What is the specific gravity of this gas? How may lights be 
extinguished by this gas in a manner to puzzle those who are not in the secret 1 
What is a good test for earbonic aeid ? 



176 CARBONIC OXIDE. 

the smallest quantity of this gas is blown into it. The 
small quantity of carbonic acid which is generated in the 
lungs at every inspiration, is sufficient to form a precipitate 
in lime water. ( See Respiration. ) 

The cause which renders lime water turbid by being 
mixed with carbonic acid is easily understood. Water 
dissolves a sm.all quantity of lime which it holds in solu- 
tion ; but carbonate of lime is insoluble in water. When 
carbonic acid is blown into a vessel of lime water, the lime 
instantly combines with it, forming a carbonate of lime, 
which, being insoluble, is seen in the form of a white cloud. 
The carbonate thus formed, being heavier than water, sinks 
to the bottom, or is precipitated. 

336. The large quantities of this acid which are formed 
by combustion and respiration, it might be supposed, would 
increase the quantity in the atmosphere, particularly in 
crowded manufacturing cities, so as to make the air 
poisonous. But as already explained, the wisdom of Om- 
nipotence has prevented the accumulation of this gas in 
particular places, in consequence of its specific gravity ; for 
experiment shows, that notwithstanding the great difference 
existing among the gases in this respect, they all mix 
uniformly. Hence, by this wonderful provision, or excep- 
tion to the general law of gravity, this gas, though extri- 
cated in immense volumes in the the free open air, soon 
diffuses itself on all sides, and mixes with the surrounding 
atmosphere, so as seldom to prove deleterious by loca^ 
accumulation. 

The composition of this gas has been determined with 
accuracy, and as seen at the head of this section, it is com- 
posed of 2 proportions of oxygen, 16, and 1 proportion of 
carbon, 6 ; hence its combining weight is 22. 

CARBONIC OXIDE, 14. 

1 eq. Carbon, 6+1 eq. Oxygen, 8. 

337. When two parts of chalk, and one of iron fiHngs, 
are mixed together and heated in a gun-ban'el, carbonic 
oxide gas is obtained. 

The student will readily understand the principle of its 

What effect is apparent when a little of this gas is blown into lime water? 
Why does lime water become turbid by the presence of carbonic acid ? Why 
IS the atmosphere seldon rendered poisonous by the accumulation of this gas ? 
What is the composition of this gas, and what its combining number ? How 
is carbonic oxide formed? 



SULPH'JR. 177 

formation. An oxide contains too small a pioportion of 
oxjgen to form an acid. When lime or chalk is heated, 
carbonic acid is extricated, and when iron is heated, it has 
a strong attraction for oxygen. When, therefore, the chalk 
and iron filings are heated together, we may suppose, in the 
first place, that the carbonic acid is extricated, as usual, but 
that the iron instantly absorbs one half of its oxygen, thus 
converting the acid gas into an oxide. 

This gas possesses the mechanical properties, color, and 
transparency of carbonic acid. Like that gas, it extin- 
guishes the flame of burning bodies, but is itself inflammable, 
the light which it puts out, setting it on fire at the surface, 
where it burns quietly, with a pale, lambent flame. The 
combining portion of carbon has been determined from this 
compound, its elements, carbon and oxygen, having never 
been found to combine in smaller proportions than 6 of 
carbon and 8 of oxygen, by weight. 

SULPHUR, 16. 

Equivalent, 16. 

338. Sulphur is found in the vicinity of volcanoes in large 
quantities, being sublimed, or brought up from the depths 
below, by the heat of the volcano, where it existed in com- 
bination with the metals. It is also found combined with 
various metals, forming sulphurets, a class of compounds 
hereafter to be examined ; nor is it entirely wanting in the 
animal and vegetable kingdoms, many substances in each 
containing it in small quantities. 

Sulphur is a well known brittle sohd, of a greenish yel- 
low color, which has little or no taste, but which emits a 
peculiar odor when heated, or rubbed. 

Its specific gravity is nearly 2, water being 1. When 
heated to a temperature a little above boiling water, it melts, 
and becomes completely fluid. In this state it is cast into 
moulds, and is known in commerce under the name of roll 
brimstone. If the heat is raised to 300°, it loses its fluidity, 
becomes viscid, and acquires a reddish color. If in this 
state it be poured into water, it becomes ductile, and is then 

What are the chemical changes which take place in forming this gas by 
means of chalk and iron filings ? What are the properties of this gas ? 
What is its composition and combining number? In what situation is 
sulphur chiefly found ? Whence comes the sulphur found in the vicinity 
of volcanoes ? How is sulphur described ? What is its specific gravity ? 
At what degree of heat does sulphur melt ? What is roll brimstone ? 

8* 



178 SULPHUR ASD OXYGEN. 

eu; ployed to take the impiessions of medals and seals. 
Tiio color and texture of these false medals have the appear- 
ance of some metaUic alloy, and those who are unacquamted 
with their composition, taking them for such, are at first 
surprised at their hghtness. 

339. When sulphur is heated to 500*^ in a close vessel, it 
rises in vapor, or sublimes^ and is condensed unchanged, 
except in form, which is that of an impalpable powder, well 
known under the name oi flowers of sulphur. In this man- 
ner it is purified. 

Sulphur combines with the earths, alkalies, the metals, 
and with several proportions of oxj^gen. Its compounds are 
therefore numerous, and some of them interesting. It has 
not been found to combine with any substance in a less pro- 
portion than 16, with which it forms an acid, called the hypo- 
sulphurous, when united to 8 parts of oxj'gen. 

Sulphur, so far as known, is a simple body ; all attempts 
to decompose it having proved fruitless. 

SULPHUR AND OXYGEN. 
SULPHUROUS ACID, 32. 

1 eq. Sulphur, 16 + 2. eq. Oxygen, 16. 

340. When sulphur is burned in pure oxj^gen gas, the 
latter suffers no change of volume, but acquires a most suf- 
focating and pungent odor, and many new properties, entirely 
different from those of oxj^gen. The compound so formed 
is sulphurous acid gas. It is colorless and transparent ; 
extinguishes flame and animal life ; and first turns vegetable 
blue colors to a red, and then destroys them. When diluted 
with a large proportion of atmospheric air, it is still so acrid 
as to produce a sense of suffocation and violent coughing 
on those who attempt to breathe it. 

It is the same gas which is formed when sulphur is burned 
in the open air, but when burned with oxygen it is pure and 
undiluted. It possesses the property of bleaching linen, silk, 
straw, &c., and hence is employed by milliners and others 
for this purpose. 

Its specific gravity is more than double that of atmospheric 
air, and hence it may be kept for some time in jars by merely 

How is sulpliur prepared to take the impressions of medals and seals ? How 
are flowers of sulphur prepared? With what other bodies does sulphur com- 
bine ? What is the lowest proportion in which sulphur is known to combine ? 
Is it an element or a compound '. How is sulphurous acid gas produced ? 
What effect does this gas produce un flame, animal life, and vegetable colors? 
How does this gas differ from that produced by burning sulphur in the air? 



SULPHUR AND OXYGEN. 179 

covering them with a piece of glass. Its equivalent compo- 
sition is 16 sulphur and 16 oxygen. Its bleaching property 
may be shown, by introducing a red rose, or other colored 
flower, into a jar containing it, which will soon become 
white. The rose must first be moistened, otherwise the 
experiment will not succeed. The color may again be 
restored by an alkali. This gas has a strong disposition to 
unite with another proportion of oxygen, and hence it will 
revive some metallic oxides, by depriving them of their 
oxygen. 

This property may be used as the means of making an 
interesting experiment. 

341. Make a solution of acetate (sugar) of lead in pure 
water, and with it moisten a piece of ribbon, or a small plant, 
such as a sprig of mint. The thing moistened of course 
presents no other appearance than if wet wittu common 
water, but when plunged for a moment into a jar of this gas, 
it comes out completely covered with a coat of brilhant 
metallic lead. 

This chemical change is thus explained. The acetate of 
lead is an oxide of the metal, dissolved in the acetic acid, or 
vinegar. The sulphurous acid having a stronger attraction 
for oxygen than the lead has, the acetate is decomposed by 
being deprived of its oxygen by the acid, and is thus revived, 
or brought to its metallic state. 

According to Mr. Faraday, the sulphurous acid is con- 
densed and brought into the liquid state, by being submitted 
to the pressure of two atmospheres, which is equal to that of 
30 pounds to the square inch. 

This acid unites with metalhc oxides, and forms salts, 
called sulphites. 

SULPHURIC ACID, 40. 

1 eq. Sulphur, 16+3 eq. Oxygen, 24. 

OIL OF VITRIOL. 

342. Sulphuric acid is an article of considerable conse- 
quence in commerce and the arts, and is prepared in large 
quantities in Europe and America. 

What is the specific gravity of this gas ? What is its equivalent composi- 
tion ? How may the bleaching property of this gas be shown ? How may 
the color of the rose again be restored? How may a ribbon, or small plant, 
be covered with metallic lead by means of this gas ? What are the chemical 
changes which take place in reviving the lead by this acid ? How may this 
acid be condensed to a liquid state ? What are the salts called which this 
acid forms with metallic oxides ? 



ISO SULPHUR AND OXYixE.N. 

It was formerly obtained by the distillatioii ot a well 
known substance called green vitriol, or copperas, and was 
tlierefore called oil of vitriol. The composition of this acid, 
as above seen, gives it the name of sulphuric acid; and green 
vitriol, therefore, which is composed of this acid and iron, is 
the sulphate of iron. 

By distilling this substance at a high heat, it is decom- 
posed, and the acid is obtained in the form of a dense, 
colorless liquid, of an oily appearance, which emits copious 
white fumes in the air. If this liquid be again distilled at a 
lower degree of heat, into a receiver surrounded with ice, 
there will pass over a colorless vapor, which will condense 
in the receiver, in the form of a white crystalline solid. This 
solid is dry, or anhydrous sulphuric acid, so called, because 
it contains no water. 

343. The sulphuric acid of commerce is this solid dis- 
solved in water. This acid is prepared by the combustion 
of 8 parts of sulphur mixed with 1 part of nitre, in large 
chambers lined with sheet lead. The acid is formed in the 
state of gas, and is absorbed by a thin stratum of water 
placed on the floor of the chamber. The following is the 
theory of this process. The sulphurous acid, formed by the 
burning sulphur, takes a portion of oxygen from the nitre, 
and is converted into sulphuric acid. This acid then com- 
bines with the potash of the nitre, and displaces nitrous and 
nitric acids in vapor. These vapors are decomposed by the 
sulphurous acid into nitrous gas, or deutoxide of nitrogen. 
This gas, suddenly expanded by the heat, rises to the roof 
of the chamber, where there is an aperture communicating 
with the open air. There it absorbs a portion of oxj-gen 
from the atmosphere and is converted into nitrous acid vapor, 
which, being a heavy aeriform bodj^, immediately falls 
down upon the sulphurous flame, and imparting a portion 
of its oxygen to the sulphurous acid vapor, converts it into 
sulphuric acid, which is then absorbed by the water. The 
nitrous acid vapor, being thus re-converted into nitrous gas, 
again ascends to the roof of the chamber for another dose of 
oxygen, with which it descends as before, and thus the pro- 
cess continues. 100 parts of nitre, and 800 of sulphur, will 
produce 2000 parts of the acid. 

How was sulphuric acid formerly obtained ? What is the chemical name 
of copperas ' How is the dry, or anhydrous sulphuric acid procured ? 01 
what does the liquid sulphuric acid of commerce consist ? Describe the man 
acrin which the sulphuric acid of commerce is prepared? 



SULPHUR AND OXYGEN. 181 

344. From Dr. Ure's paper on this subject, we learn that 
the common acid of the shops contains from 3 to 4 per cent, 
of foreign matter, consisting chiefly of sulphate of potash, 
and sulphate of lead, and that it often contains much more 
than these proportions, in consequence of the introduction of 
nitre, to remove the brown color, accidentally given the acid 
by bits of wood, or straw. 

The purest sulphuric acid obtained by the usual process, 
has a specific gravity of about 1845, water being 1000. If 
it is much heavier than this, adulteration by means of some 
ponderous substance may be suspected ; and if much hghter, 
its strength will probably be found deficient in consequence 
of dilution with water. In consequence of the strong attrac- 
tion of this acid for water, with which it unites in all pro- 
portions, it absorbs moisture from the air with avidity, and 
thus when vessels containing it are left open, they gain in 
weight, instead of losing by evaporation. If carboys of this 
acid are permitted to stand in a damp place, as in a cellar, 
with the stoppers left out, there will probably be a gain in 
weight, which will amount to much more than the interest 
of the money the acid cost. It therefore becomes honest 
dealers, as well as careful buyers, to see that this acid is 
well secured from contact with the air. 

345. This acid is one of the most caustic and corrosive of 
all substances. When mixed in the proportion of four parts 
of acid with one of water, the temperature of the mixture 
rises to 300°. Its extreme activity, as a caustic, seems to 
depend on its avidity for moisture, and the heat occasioned 
by the union. On the entire skin, when this is dry, it pro- 
duces no immediate effect, but if there is the smallest erosion, 
or scratch, it operates on that part instantly, and with the 
most intense and painful energy. The flesh appears to be 
first burned, and then dissolved by its action. 

In case of any accident, where the concentrated acid is 
thrown upon the clothes, or skin, as it is generally known 
that this acid burns, the spectators run for water, which is 

What impurities does the sulphuric acid of commerce always contain? 
What proportion of these substances does the common sulphuric acid of the 
shops contain ? How may the quantity of foreign matter in this acid be as- 
certained ? What is the specific gravity of the best sulphuric acid, obtained 
by the usual process ? What is said of the absorption of water by this acid, 
when left open ? In what proportions does a mixture of this acid and water 
produce the greatest degree of heat ? On what does the causticity of this acid 
seem to depend? In case this acid is accidentally thrown upon i person 
what is said to be the best method of neutralizing its pfT.\-r= ' 



182 PHOSPHORUS. 

thrown on, with the intention of diluting; the acid, and thus 
to prevent its farther action. This, though meant in kind- 
ness to the sufferer, might be the means of his destruction ; 
for the degree of heat, thus raised, would be sufficient to de- 
stroy his skin, without the farther action of the acid. In 
such cases, there is much less danger in waiting until some 
potash, chalk, or even ashes, can be procured, and thrown 
on the part. Meantime, the sufferer should be stripped of 
the clothing on which the acid has fallen, and the acid ab- 
sorbed from the skin with a moistened sponge, or cloth, or 
even a handful of dry clay, thrown upon the part. 

Strong sulphuric acid boils at 620°, and freezes at 15° 
below zero. 

The dry acid is composed of 

1 equivalent of sulphur, 16 
3 do. of oxygen, 24 

40 

The common or hydro-sulphuric acid contains, in addition 
to the above, one proportion of water, making its equivalent 
number 49. 

PHOSPHORUS. 

Equivalent, 16. 

346. Phosphorus is a yellowish, inflammable solid, which 
in the open air emits white fumes, and at common tempera- 
tures is luminous in the dark. 

This substance has never been found in a simple state, 
but is combined with animal substances, in considerable 
quantities, and is occasionally found in minerals. 

It is obtained from bones by the following process : In 
the first place, the bones are calcined, or burned in an open 
fire, and then pulverized, and digested for two or three days 
with half their weight of sulphuric acid, to which water is 
occasionally added. This solution is then mixed with twice 
its bulk of hot water, and the liquid separated by straining 
through a cloth. By this process, the bones, which are 
composed of phosphoric acid and lime, are decomposed, and 
two new salts, viz., the sulphate oflime^ and the hiphosphate 

What is the composition of the dry acid ? What quantity of water does 
the strongest common acid contain? What is the equivalent number for the 
hydrosulphuric acid ? What is phosphorus ? In what state is phosphorus 
found, in a simple or combined state? By what process is phosphorus ob 
tained ? 



PHOSPHORUS. 183 

of lime^ are formed. The sulphate of hme is insoluble in 
water, and therefore the filtrated solution contains only the 
biphosphate, which is soluble. Thus, the bones, which are 
a phosphate of lime, mixed with animal matter, are first de- 
prived of this matter by burning, and then converted, in part, 
into the biphosphate by the sulphuric acid. We have, then, 
in this stage of the process, a solution of the biphosphate, or 
acidulous phosphate of lime in water. This solution is then 
evaporated to the thickness of syrup, mixed with one fourth 
of its weight of charcoal in powder, and distilled with a 
strong heat, in an earthen retort. The charcoal combines 
with the oxygen of the biphosphate, which, being thus de- 
composed, the phosphorus distils over, and is obtained in a 
vessel of water, into which the mouth of the retort is placed. 

347. Phosphorus, thus obtained, is of a yellowish, or flesh 
color, but may be made colorless and transparent by re- 
distillation. 

This substance is exceedingly inflammable, so that at 
common temperatures, it is necessary to preserve it under 
water, in well stopped bottles. It may be set on fire by 
shght friction, or even by the heat of the hand. It is insol- 
uble in water, but is soluble in ether, or oils, to which it 
communicates the property of shining in the dark. 

Put a piece of phosphorus into a vial half filled with olive 
oil, then keeping the thumb on the mouth of the vial, warm 
the bottom, shaking it now and then, until the phosphorus 
is melted This forms liquid phosphorus^ and a vial thus 
prepared may be occasionally useful to show the hour ot 
the night by a watch. All that is necessary for this pur- 
pose is to hold the vial in the hand for a few minutes, until 
it becomes warm, then take out the cork, and the union of 
the oxygen of the air with the phosphorus will evolve 
sufficient hght to see the hour. 

That the light is owing to the combination of oxygen 
with the phosphorus, or to its slow combustion, in the above 
instance, is proved by the fact, that phosphorus may be 
melted and sublimed in pure nitrogen, without the least 
appearance of light. Its combustion in oxygen gas is 

Describe the different chemical changes which take place in the process of 
its preparation. What is said of the inflammability of phosphorus ? In what 
manner must it be preserved from the air ? How is liquid phosphorus pre- 
pared? For what purpose may a vial of this mixture be useful? How is 
it proved that the luminous appearance of phosphorus is owing to the absorp 
tion of oxygen ? 



iri4 PHOSPHORUS AND OXYGEN. 

exceedingly vivid, and affords a striking and splendid experi- 
ment for a public lecture room. 

When taken into the stomach, phosphorus proves a vim- 
lent and deadly poison ; though in minute doses, it has been 
used as a medicine, when dissolved in ether. 

PHOSPHORUS AND OXYGEN. 

PHOSPHORIC ACID, 32 

1 eq. Phosphorus, 16+2 eq. Oxygen, 16. 

348. Phosphorus, as above stated, unites with oxygen 
with great rapidity, and aifords an instance of intense chemi- 
cal action, attended with the most brilhant phenomena. 
During this combustion, copious white vapors are produced, 
which fall to the bottom of the vessel in which the experi- 
ment is made, like flakes of snow. This white vapor is 
the dry, or anhydrous phosphoric acid. If exposed to the 
air, it soon attracts moisture in sufficient quantity to dis- 
solve it, and thus becomes liquid phosphoric acid. 

This acid may also be formed by the action of nitric acid 
on phosphorus. The union is made by dropping pieces of 
phosphorus into the strong acid. The phosphorus absorbs 
one proportion of oxygen from the acid, thus converting this 
acid into the deutoxide of nitrogen, or nitrous gas, which 
escapes in immense volumes during the process. The phos- 
phorus is thus converted into phosphoric acid, which is 
obtained in the solid form by evaporating the solution to 
dryness. 

Phosphoric acid unites with water in all proportions, and 
produces a small degree of heat during the solution. Its 
taste is intensely sour, but it is not corrosive. When 
heated in contact with charcoal, the latter absorbs its 
oxygen, and the phosphoric acid is converted into phos- 
phorus. This acid combines with various bases, and forms 
a class of compounds called phosphates. Its composition is 

1 proportion of phosphorus, 16 

2 do. of oxygen, 16 

Consequently its equivalent is 32 

What is said of the poisonous quality of this gas when taken into the 
stomach ? What is said of the union of phosphorus and oxygen ? In 
what form does the dry phosphoric acid appear? Why does this acid 
jecome liquid on exposure to the air ? By what other method may this acid 
be formed ? When phosphorus is thrown into nitric acid, what are the 
chemical changes which ensue 1 Li what manner does charcoal convert 
phosphoric acid into phosphorus ? 



PHOSPHOROUS ACID 185 

PHOSPHOROUS ACID, 24 

1 eq. Phosphorus, 16+1 eq. Oxygen, 8. 

349. This acid is obtained by exposing pieces of phos- 
phorus to the open air, in consequence of which it sponta- 
neously absorbs oxygen, and undergoes a slow combustion 

If tw^o or three sticks of phosphorus be thus exposed in a 
glass funnel, set into the mouth of an empty bottle, the acid 
will be formed, and by attracting moisture from the air, wih 
be dissolved, and pass down into the bottle, where at first 
may be found a quantity of Hquid phosphorous acid. This 
acid combines with different bases, and forms salts, which 
are called phosphites. Phosphorous acid, when exposed for 
some time to the air, absorbs another proportion of oxygen, 
and is then converted into phosphoric acid. Indeed the 
acid formed by this method is probably always mixed with 
the phosphoric acid. 

There are several other compounds of phosphorus and 
oxygen, but these are the most important. The phosphates 
will be described in their proper place. 

BORON, 20. 

350. There is a solid substance, resembling alum in ap- 
pearance, which is used in medicine and the arts, under 
the name of horax. From borax there is extracted an acid, 
called the horacic acid. When boracic acid is heated in 
contact with the metal called potassium.^ the metal, having a 
strong affinity for oxygen, deprives the acid of that prin- 
ciple, and thus its base, called horon.^ is set free. This, so 
far as is known, is an element. Boron is insoluble in water, 
alcohol, or oil. It may be exposed to the strongest heat in 
a close vessel, without change, but when heated to about 
600° in the open air, it takes fire, burns vividly, and by the 
absorption of oxygen, is again converted into boracic acid. 

Boracic Acid. — This is the only known compound of 
boron and oxygen. It is a natural product, occasionally 
found in springs, and also in several salts, of which borax, 
or the borate of soda., is the principal. 



What is the composition and what the combining number of this acid ? How 
is phosphorous acid obtained ? What are the salts called which this acid 
forms with the different bases ? How is boron obtained ? Is boron a com- 
pound, or an elementary body ? What are the properties of boron ? What 
is boracic acid ? 



15 



186 CHLORINE. 

The acid may be obtained from the borate of soda, by 
dissolving- that substance in hot water, and then adding sul- 
phuric acid until the solution becomes sour. Sulphuric acid 
cornbmes with the soda, forming sulphate of soda, or Glau- 
ber's salt, while the boracic acid thus set free, is formed 
when the water cools, in small crystals. It is not readily 
soluble in water, but alcohol dissolves it freely, which being 
set 0". fire, burns with a beautiful green flame. This green 
flame is a good test of the presence of boracic acid in any 
composition. 

This acid is composed of 

Boron, I equivalent, 20 
Oxygen, 6 do. 48 

The combining p. of this acid is therefore 68 

CHLORINE. 

Equivalent, 36. 

OXMURIATIC ACID. 

3.51. This highly important and useful gas is obtained by 
the action of muriatic acid on black, or peroxide of manga- 
nese. The most convenient mode of preparing it is by mix- 
ing strong muriatic acid, contained in a retort, with half its 
weight of the black oxide of manganese in fine powder, and 
then applying a gentle heat. The gas may be received in 
glass bottles filled with water, and inverted in the pneumatic 
cistern, in the usual way. The water should be wanned, 
to prevent absorption. 

352. A cheaper mode of obtaining this gas, is to mix 
three parts of sea-salt, powdered, with one of the manganese, 
in a tubulated retort, (Fig. 39,) and then to pour in two 
parts of sulphuric acid, diluted with an equal quantity of 
water. By the heat of a lamp, the gas will be extricated in 
abundance. 

This gas is of a yellowish green color, the name, chlo- 
rine, in Greek, signifying green. It has an astringent taste, 
and is so exceedingly suffocating, that a bubble or two let 
loose in a room, will excite coughing and a sense of stran- 

How may boracic acid be obtained ? What is the common name for borate 
of soda ? What is the best test for the presence of boracic acid ? What are 
^he elements of boracic acid, and what is its combining number? How is 
"inlorine obtained? What are the two processes, described, of obtaining it f 
What is said of the color and suffocating effects of this gas ? 



CHLORINE. 187 

gulation. Cold water, recently boiled, will absorb twice its 
volume of chlorine, which it gives out again on being heated 
The specific gravity of this gas is 2.5, so that it is more 
than twice as heavy as atmospheric air. 100 cubic inches 
weigh 76.25 grains, while the same quantity of common air 
weighs only 30.5 grains. 

353. Chlorine, in solution with water, was formerly called 
oxymuriatic acid, from the opinion that it was composed of 
muriatic acid and oxj^gen. But according to the logic of 
chemistry, it is now universally considered a simple body, 
having never been decomposed, though repeatedly submitted 
to the most active decomposing agents known to chemists. 
Sir H. Davy submitted it to the most powerful effects of gal- 
vanism, and to charcoal heated to whiteness, without de- 
composition, and without separating the least trace of 
oxygen from it. Hence, according to the present state of 
knowledge, it is an elementary body. 

Chlorine is a supporter of combustion. When a lighted 
taper is plunged into this gas, it burns with a small red 
flame, emitting a large quantity of smoke. Phosphorus 
takes fire in it spontaneously, and so do several of the metals. 

Fill a deep bottle, or large tube, with this gas, and set it 
upright, with the mouth covered by a plate of glass. Have 
some antimony prepared, by being pounded in a mortar; 
then slide off the cover and pour in the metal. It will take 
fire before it reaches the bottom, and afford a beautiful 
shower of white flame. This affords an elegant and striking 
experiment. The metals, tin, zinc, copper, arsenic, and 
even gold, when in the state of powder, or thin leaves, will 
be inflamed in the same manner. 

354. Chlorine has a very strong attraction for hydrogen, 
but it is through the mysterious influence of light that the 
combination between the two substances seems sponta- 
neously to be effected. 

Thus, when a mixture of these two gases is kept in the 
dark, no combination ensues, but if exposed to the direct 
light of the sun, they combine suddenly, and with a violent 
detonation. This sometimes happens without the sun's light. 



What is its specific gravity ? What was the former name of this gas ? 
Does this gas contain any oxygen ? What is said of the experiments of Sir 
H. Davy on chlorine ? Is this an elementary, or a compound body 1 Is chlo- 
rine a supporter of combustion ? What substances take fire in this gas spon- 
taneously ? In what manner may a shower of flame be made by this gas and 
a metal ? What is said of the union between this gas and hydrogen ? 



.88 CHLORINE AND HYDROGEN. 

Tins g;as, though formerly called an acid, does not appear 
to possess any acid properties. It is not sour to the taste, 
nor does it redden vegetable blue colors, properties nearly 
universal in the acids. 

But the most important property of chlorine, is its bleach- 
ing power, all vegetable and animal colors being discharged 
by its action. For this purpose, it is combined with quick- 
lime, forming chloride of lime, or bleaching powder^ an article 
very extensively employed at the present time, and which 
will be described, and its properties examined, in its proper 
place. 

Another very important property of chlorine is its disin- 
fecting power, any infectious or disagreeable odor being 
almost instantly destroyed by it. For this purpose, the 
chloride of lime is also chiefly employed. The compounds 
of chlorine which are not acid, are called chlorides^ or chlo- 
rurets. When chlorine, united to oxygen, com.bines with a 
base, and forms a salt, it is called a chlorate. These were 
formerly called hy per oxy muriates. They possess no bleach- 
ing properties. 

CHLORINE AND HYDROGEN. 

HyCROCHLORlC ACID, 37. 

1 eq. Chlorine, 36-f 1 eq. Hydrogen, 1. 

355. We have just seen that chlorine has a strong affinity 
for hydrogen, but that no union takes place between them, 
without the influence of hght. When the light is entirely 
excluded, a mixture of these gases remains without change. 
When the mixture is made in a glass vessel, and exposed to 
the hght of day in the shade, the gases, if of equal volumes, 
slowly combine, and form muriatic acid gas. But when the 
mixture is exposed to the direct rays of the sun, the union 
is sudden, and attended by an explosion. 

This combination does not change the volume of the ori- 
ginal mixture, but the properties of the two gases are greatly 
changed. If the vessel in which the experiment has been 

Does chlorine contain any of the properties of an acid ? What is the most 
important property of chlorine ? What does chlorine form, when combined 
with quicklime? What other important and useful property has this gas? 
What are the compounds of chlorine, which are not acid, called ? When a 
mixture of hydrogen and chlorine is kept in the dark, what change takes 
place? When placed in the shade, what is the effect? When the mixture 
is placed in the sun, what effect is produced? What are the changes pro- 
duced on these gases by this combination ? 



CHLORINE AND HYDROGEN. 1 89 

made is unstopped under water, the fluid will in a few mo- 
ments entirely absorb its contents, and fill the vessel in its 
place, while the two gases, before combination, were ab- 
sorbed by water only in small proportions. The peculiar 
odor of chlorine, and its prompt bleaching property, are also 
destroyed, and other change of properties will become appa- 
rent on further examination. 

The compound formed by the union of chlorine and hy- 
drogen is called hydrochloric acid. This gas is composed 
by weight of 

1 equivalent of chlorine, 36 
1 do. of hydrogen, 1 

Combining weight of hydrochloric acid gas, 37 

356. The production of muriatic acid by the combination 
of its elements, is designed to prove its constitution, and com- 
bining proportions. This acid is, however, much more 
readily prepared by the action of sulphuric acid on com- 
mon salt. 

If the salt be pulverized and mixed with an equal weight 
of the acid, and then the heat of a lamp applied, muriatic 
acid gas will be disengaged. But it must not be received 
over water, which will absorb several hundred times its own 
bulk of this gas. 

Muriatic acid gas is a transparent, elastic fluid, of a very 
pungent smell, and intensely acid taste. Its attraction for 
water is so great, that when it escapes in the open air, even 
in the dryest season, it instantly forms a white cloud, in con- 
sequence of combining with the moisture of the atmosphere. 

Water, at the temperature of 40°, absorbs 480 times its 
bulk of this gas, and the solution is known under the name 
of muriatic acid, or spirit of sea salt, and is largely employed 
for chemical and manufacturing purposes. 

This acid is prepared, in the large way, by extricating 
the gas from sea salt, by sulphuric acid, as above described, 
and then passing a current of it into water, as long as any 
is absorbed. It forms, with the different bases, a class of 
salts, called muriates, or hydrochlorates. 



What is the name of the new gas ? What is said of the absorption by water 
of chlorine, and hydrogen, and also of muriatic acid gas ? What is the com 
position of muriatic acid gas, and what is its combining number ? How is this 
gas most readily and conveniently prepared? Why does muriatic acid gas 
form a white cloud in the open air? How many times its own bulk of this 
gas will water absorb? Under what name is this solution of gas in water 
known ? How is the muriatic acid of commerce prepared ? 



190 CHLORINE AND SULPHUR. 

When this gas, in a pure state, is submitted to the pressure 
of 40 atmospheres, that is, 600 pounds to the square inch, it 
is condensed into a Hquid. 

CHLORINE AND OXYGEN. 

357. There are four compounds of chlorine and oxygen^ 
formed bj the union of as many different proportions of the 
oxygen to the same proportions of chlorine. These com- 
pounds are known only to chemists, and with the exception, 
perhaps, of chloric acid, possess no value in the arts. They 
are all formed by the action of an acid on the chlorate of 
potash, or the chlorate of barytes. The chief interest which 
these substances possess, in a chemical relation, is their 
strict conformity to the laws of definite and multiple propor- 
tions. Their names and constituents are as follow : 



Protoxide of chlorine. 


, 36 chlorine + 8 > 


oxygen. 


Peroxide of chlorine. 


36 


u 


+ 32 


u 


Chloric acid, 


36 


u 


+ 40 


a 


Perchloric acid, 


36 


il 


+56 


li 



Thus, the first is composed of 1 proportion of chlorine 
combined to 1 of oxygen. The second, 1 of chlorine and 4 
of oxygen. The third, 1 of chlorine and 5 of oxygen. The 
fourth, 1 of chlorine and 7 of oxygen. 

The equivalent numbers, therefore, for the first, is 36+8 = 
44; the second, 36 + 32 = 68; for the third, 36+40 = 76 ; 
and for the fourth, 36 + 56=92. 

CHLORINE AND SULPHUR. 

CHLORURET OF SULPHUR, 52. 

1 eq. Sulphur, 36+1 eq. Chlorine, 16. 

358. The combination of chlorine with sulphur forms a 
curious compound, called chloruret of sulphur. The method 
of forming this combination is as follows : 

The materials for making chlorine, it will be remembered, 
are black oxide of manganese, and muriatic acid. These 
being placed in the flask, «, Fig. 69, and the heat of a lamp 
applied, the chlorine will rise, and pass down the tube into 
the globe, 5, where any water it contains is condensed. 

Under what pressure is this gas condensed into a liquid? How many 
'ompounds of chlorine and oxygen are known ? Do the compounds of chlo- 
rine and oxygen possess any value in the arts? In what relation are .ne 
compounds of chlorine and oxygen interesting? 



CHLORINE AND SULPHUR. 
Fig. 69. 



191 




Rising from 5, the gas passes through the tube, c, contain- 
ing chloride of calcium, by the absorption of which, it will 
be deprived of all moisture, so that it will arrive at e, which 
contains the sulphur, in a perfectly dry state. The globe, 
e, must be gently heated by means of a spirit lamp, so as to 
melt the sulphur. 

By these means, the sulphur and chlorine are made to 
combine and pass in the gaseous state into the globe, /, 
which being kept cold by means of a stream of water from 
the cistern, 7^, the compound is condensed into the liquid 
form. The quantity of water is regulated by means of the 
stop-cock, z, affixed to the tube, ^, and falls from the globe 
into the dish, o. The superfluous gas passes off into the 
open air, by the waste pipe, I. By this method small quan- 
tities of the chloruret of sulphur may be formed. 

Chloruret of sulphur is a yellowish red fluid, of a pecu- 
liar and disagreeable odor, whose boiling point is 346°. It 
sinks in water, by which, in a short time, it is decomposed, 
and resolved into hydrochloric and sulphuric acids, and sul- 
phur. The chlorine combines with the hydrogen of the 
water, while the oxygen of the water combines with one 
fourth part of the sulphur thus set free to form sulphuric 
acid. The remaining three parts of the sulphur are separa- 
ted in the solid form. 

Chloruret of sulphur is composed of 100 parts of sulphur, 
and 110 parts of chlorine, by v/eight. 

By allowing chlorine to pass over this compound for a 
time, another portion is absorbed, and a new compound is 
formed, which contains twice as much chlorine as the 
chloruret ; this is a chloride of sulphur, and is full of a dull 
red color. 



.92 CHLORINE AND NITROGEN. 

The chloruret dissolves sulphur, and is capable of taking 
up much more when heated than when cold. Hence, if the 
heated solution be saturated, and then cooled, beautiful 
crystals of sulphur are deposited. 

CHLORINE AND NITROGEN. 

CHLORIDE OF NITROGEN, 158. 

4 eq. Chlorine, 144+1 eq. Nitrogen, 14. 

359. This curious compound was discovered bj Dulong^, 
a French chemist, in 1811. Chlorine and nitrogen have 
but a very slight affinity for each other, but they may be 
made to combine, by passing a current of the first through 
a solution of nitrate of ammonia. (Nitric acid, it may be 
remembered, consists of the two elements, oxygen and nitro- 
gen, and ammonia is composed of hydrogen and nitrogen. 
By the union of these two compounds, nitrate of ammonia 
is formed.) To prepare chloride of nitrogen, dissolve an 
ounce or two of the nitrate of ammonia, in 14 or 16 ounces 
of hot water, and when the solution has cooled to about 90°, 
invert in the solution a glass jar, with a wide mouth, filled 
with chlorine. The solution gradually absorbs the chlorine, 
and consequently, rises in the jar, at the same time acquir- 
ing a yellow color. In about half an hour, minute globules, 
of a yellow fluid, like oil, are seen floating on its surface. 
These, by uniting, acquire the size of small peas, when they 
sink to the bottom of the vessel. These globules are the 
chloride of nitrogen. They are formed by the decomposi- 
tion of the ammonia, in the solution ; the chlorine combining 
with its nitrogen, and thus forming the compound in ques- 
tion. A cup of lead, or glass, should be placed at the bottom 
of the solution, and under the mouth of the jar, to receive 
the product. 

The chloride of nitrogen is the most violently explosive 
substance yet discovered, and should not be experimented 
upon by the student, in quantities larger than a mustard 
seed at a time, and even in this quantity, with great cau- 
tion. Both its discoverer, and Sir H. Davy, notwithstanding 

What is the atomic weight, or chemical equivalent of chlorine ? What are 
the names, and what the combining numbers, of the four compounds of chlo 
rine and oxygen? What is said of the affinity between chlorine and nitre 
gen? What is the composition of nitrate of ammonia? How is the chloride 
cf nitrogen prepared? What chemical changes take place in the formation 
of chloride of nitrogen? What cautions are given with respect to experi- 
menting on this compound ? 



IODINE 193 

their experience and caution as chemical experimenters, 
v/ere seriously injured by its violence. At the temperaturn 
of about 200° it explodes, and at common temperatuVes, 
when thrown on some combustibles. When a small globule 
is thrown into olive oil, or spirit of turpentine, it explodes 
with such violence as to shatter any vessel of glass in pieces. 

The violence of its detonation is owing to the great vol- 
ume of the products which are formed at the instant. The 
compound consists wholly of the two gases, chlorine and 
nitrogen, condensed, and combined with each other. When, 
therefore, the explosion takes place, these two elements 
assume their gaseous forms, thus, in an instant, occupying 
a vast space, when compared to their fcrmer state. 

Chloride of nitrogen consists of 

1 equivalent of nitrogen, 14 
4 do. of chlorine, 144 

Making: its number, 158 



Equivalent, 125. 

360. The next simple substance we shall examine, is 
iodine. Its name signifies, va Greek, "violet colored," 
because, when in the state of Vc^por, it is of a most beau- 
tiful violet color. 

Iodine was discovered at Paris by a manufacturer of nitre, 
in 1812. This substance is obtained from the lye made of 
the ashes of marine vegetables, or from the substance called 
kelp, or barilla^ which is an impure alkali, made during the 
manufacture of soda. The process is as follows : 

Dissolve the soluble part of kelp, or the ashes of sea- 
weeds in water ; concentrate the solution by evaporation, 
when crystals of carbonate of soda will appear, which must 
be separated. Then pour the remaining liquor into a clean 
vessel, and mix with it an excess of sulphuric acid. Boil 
this liquid for some time, and then strain it through a cloth. 
r*ut this liquid into a small flask, and mix with it as much 
black oxide of manganese, by weight, as there was sul- 

At what temperature does this compoimd explodo'? What combustible 
substances cause it to explode at common temperatures ? Explain the cause 
of Its violent explosion. What are the combining numbers for its constitu- 
ents, and also for the compound ? What does the name iodine signify, and 
from what circumstance has it derived its name 1 Bv what process is iodine 
prepared ? 

9 



194 IODINE. 

pliuri'i acid ; then attach to the mouth of the flask a glass 
tube, closed at the upper end, and apply the heat of a lamp 
to the flask. The iodine will be sublimed, and will attach 
itself to the tube in small brilliant scales resembling black 
lead. 

Iodine thus obtained is a friable solid, with a brilHant 
metallic lustre, and bluish gray color. Its taste is hot and 
acrid, and it is sparingly soluble in water. It corrodes the 
cork of the vial in which it is kept, and escapes — is a strong 
poison when taken in large doses : but in solution with 
alcohol, which dissolves it freely, has been considerably 
used as a medicine. 

When heated in a retort to about 250°, it evaporates, 
and fills the vessel with an exceedingly rich violet col- 
ored gas. As the retort cools, it again condenses in fine 
brilHant points resembling frost on the glass. If exposed to 
the open air, it slowly evaporates, and if handled, it leaves 
a brown stain on the fingers. 

361. Io(Hne resembles chlorine in smell, and in some of 
its properties, particularly in destroying vegetable colors. 
Like oxygen and chlorine, it is a non-conductor of elec- 
tricity, and is a negative electric. So far as is known, it 
is a simple body. It has a strong attraction for the pure 
metals, and the simple non-metallic substances, such as 
sulphur and phosphorus. These compounds are called 
iodides. 

From experiments made by Dr. Thompson, the atomic 
weight of iodine is 124. 

The best test for iodine, in its free state, is starch, with 
which it forms an insoluble compound in water, of a deep 
blue color. This test is so delicate as to indicate the most 
minute portion of starch in solution. 

Iodine combines with hydrogen, oxygen, and chlorine, 
fonning hydriodic acid, iodic acid^ and chloriodic acid. 
Among these, the hydriodic acid, only, is of any import- 
ance or use. 



What is the appearance of iodine ? "What are its sensible properties ? 
"Wliat are its uses ? What is the effect when it is heater) in a retort ? When 
exjiosed to the open air whal is the consetjnence ? In whal respects (io^s 
ioiiirie resetiilile chlorine? What is its electrical state? Is iodine a simple 
or a coinii()iin(i liody ? For what substance has iofliiie a strons attrnction? 
Wli;it IS the atomic weight of lodiiie ? What is the most delicate test for 
iodine? 



IODINE ANT) HYDROGEN. 195 

rODINE AND HYDROGEN 

HYDRIODIC ACID, 126. 

1 eq. Iodine, 125 + 1 eq. Hydrogen, I. 

362. When iodine is heated in a porcelain tube with hydro- 
gen gas, tiie two substances combine and form a comiiound 
in the form of a gas, which has acid properties, and which 
is rapidly absorbed by water. This is the hydriodic acid. 

This gas is without color, is very sour to the taste, red- 
dens the blue colors of vegetables, and has an odor similar 
to muriatic acid gas. 

It combines with alkalies, forming salts, called hydri- 
odates. 

The discovery of iodine was one of the means of sub- 
verting the former doctrine, that oxygen was the universal 
acidifying principle, the above instance showing that com- 
pounds, having all the properties of acids, are formed by the 
combination of hydrogen with iodine. Several other instan- 
ces of similar nature have been discovered, as in the case of 
muriatic acid. These instances appear, however, to be only 
exceptions to a universal principle, oxygen being still the 
acknowledged agent by which most acids are formed. 

363. Hydriodate of Potash. — This is given a place here, 
instead of among the salts, because it is the only salt of the 
kind to be described, and because, in manufacturing this 
compound, the method of obtaining the hydriodic acid is 
different from that stated above. It is the only hydriodate 
of any use or importance, and does not exist as a salt in a 
separate state, but only in solution. 

In preparing hydriodate of potash for medicinal use, the 
preliminary labor of forming the acid may be dispensed 
with, and the salt in solution may be formed by a very sim- 
ple process, as follows : 

Add to a hot solution of pure caustic potash in water, as 
much iodine as it is capable of dissolving. This will form 
a solution of a reddish brown color, consisting of the iodate 



How may hydriodic acid be formed? What are its sensible properties? 
What are the salts called which this acid forms with alkalies? How does 
this acid demonstrate that oxygen is not the universal acidifying principle? 
Are there any other instances in which an acid is formed without oxygen ? 
What is said relative to these exceptions to a general principle ? How is the 
hydriodate of potash formed'? What does the reddish brown solution con 
gist of? 



196 HKOMINE. 

anil hydriodate of potash, together with an excess of free 
iodine. 

'J'hroiigh this solution, a current of snlphin etted hydrogen 
gas is iransmitied, until the free iodine and iodic acid are 
converted into hjdriodic acid, changes which may be known 
to be accomplished by the appearance of the liquid, which 
will gradually lose its brown color, and become colorless 
and transparent. The solution is then heated to expel the 
remaining sulphuretted hydrogen, and after being filtered, is 
pure hj'-driodate of potash, in aqueous solution. This solu- 
tion is considerably employed, as a medicine, in scrofula, 
and other glandular diseases. 

BROMINE. 

Equivalent, 78. 

364. The name bromine is from the Greek, and signifies a 
"strong, or rank odor." 

Bromine, after undergoing various and multiplied tortures, 
by means of the most powerful decomposing agents, is 
arranged as an elementary body, having endured fire, gal- 
vanism, &c., without loss of integrity. 

It was discovered by Balard, of Montpelier, in 1826, and 
like iodine, exists in the ashes of marine vegetables, and also 
in sea water. 

The process of extricating it is too intricate to be detailed 
in this work, nor would it ever be undertaken by pupils in 
chemistry, for which this book is designed. 

Bromine is a fluid of a hyacinth red color, when viewed 
by transmitted light: but of a blackish red, when seen in the 
ordinary manner, or by reflected light. Its odor resembles 
that of chlorine, but is much more disagreeable. Like iodine, 
it corrodes wood or cork, and stains the fingers of a yellow- 
ish hue. Its specific gravity is 3. It is a strong poison. 
It is volatile at common temperatures, and emits red vapors 
similar to those of nitrous acid. 

A ligh ed taper is soon extinguished by it, but before going 
out it burns with a flame which is green at the base and red 
at the top. 

How is it known when a sufficient quantity of sulphuretted hydroeen 
has been {)assed throMgh the solution of iodine ? What is the use of the hydri- 
odate of potash ? What does the name bromine signify ? Is it an element, 
or a compound ? In what substance does it exist? What is the appearance 
of bromine ? In what respects is it similar to iodine ? 



FLUORIC ACID. 197 

Bromine does not turn blue vegetable colors red, but like 
chlorine, destroys them. 

From these properties it will be observed, that this sub- 
stance has many characters in common with iodine and 
chlorine. 

Bromine combines with oxygen, hydrogen, and chlorine, 
but these compounds are little known, and of no interest 
except to professed chemists. 

Its equivalent number, as seen at the head of this section, 
is 78. 

FLUORIC ACID. 

Equivalent, 26. 

365. It is a singular circumstance in chemistry, that the 
base of the fluoric acid has never been detached from the 
acid itself, notwithstanding every effort has been made on 
the part of the chemists to effect a separation. It will be 
remembered, that all the other acids consist of a base united 
to an acidifying principle, and that the two elements have 
been examined in separate states. Thus, sulphuric acid 
consists of sulphur and oxygen ; carbonic acid, of carbon 
and oxygen, &c. 

The base of this acid, however, has been named fluorine ; 
but whether this is united to oxygen, as the acidifying prin- 
ciple, or whether such a base exists or not, is unknown. 
Fluoric acid must, therefore, at present, be examined as a 
simple body, or in connection with substances to which it 
unites. 

This acid exists in nature in considerable quantitios, being 
found combined with lime, formmg the salt called fluate of 
lirne, but more commonly known under the name of Derby- 
shire spar. This latter substance is found crystalized, and 
of various colors intermixed, forming, when polished, one of 
the most beautiful productions of the mineral kingdom. It 
is in common use, for vases, candlesticks, snuff-boxes, &c. 

366. Process for fluoric acid. — To obtain fluoric acid, a 
quantity of fluate of lime is powdered, and submitted to the 
action of twice its weight of strong sulphuric acid, in a 
retort of lead. On the a^ plication of a gentle heat to 

In what respect does it resemble chlorine in properties ? What is the 
equivalent number of bromine ? Has the base of fluoric acid never been 
detached from the acid itself? Is the same true of any of the other acids ? 
What is the base of fluoric acid called ? Is it known that any such base 
exists? What natural substance contains fluoric acid ? How is fluoric acid 
obtained from tiaate of lime ^ 



198 



FLUORIC ACID. 




tJie retort, the acid distils over, and must be received in a 
leaden vessel. 

The retort, and receiver, 
Fig. 70, made of sheet lead, 
and saidered tof^ether on the 
edges, and the juncture be- 
tween them stopped with a 
lute of clay, will answer 
very well. The while fluor 
must be selected for this purpose, as being most pure. It 
is first put into the retort, the acid poured in, and then con- 
nected with the receiver, which must be surrounded with a 
mixture of common salt and snow, or powdered ice. 

Fluoric acid, at the temperature of 32o, or the freezing 
point, is a colorless liquid, and will retain its hquid state, if 
preserved in well stopped vessels, when the temperature is 
60°. But if exposed to the air when the temperature is 
above 32°, it flies off in dense white fumes, which consist 
of the acid, and the moisture of the air with which it corn- 
bines. 

No substance with which we are acquainted has so strong 
an affinity for water as fluoric acid. Its liquid state appears 
to be owing to the water which is distilled over from the sid- 
phuric acid during the process of obtaining it, and no process 
yet devised has succeeded in freeing it entirely from mois- 
ture. When a single drop is let fall into v/ater, a hissing 
noise is produced, like that occasioned by the plunging of a 
red hot iron into the same fluid, such is the heat produced 
by its combination witii water. 

In experimenting with this fluid, the utmost caution is 
necessary ; for no substance so instantly and effectually 
aisorganizes the flesh, and produces such deep and obsti- 
nate ulcers, as this. The least particle would inevitably 
destroy an eye, or create an obstinate ulcer on any other part. 
367. Process of Etching on Glass. — Fluoric acid has the 
singular property of corroding glass, and may be used for 
this purpose in the fluid state, as above described, or in the 
gaseous form, the latter of which is commonly the most 
convenient. 



What IS the appearance of fluoric acid at the temperature of 32° ? What 
is its appearance when exposed to the open air, at a temperature above 32°? 
What is said of the affinity of this singular acid for water ? What is said of 
the action of this acid on the flesh ? What is said of the action c fluoric 
acid on glass ? 



FLUORIC ACID. 199 

Any design may be etched on glass, by the following 
simple method : 

First, cover the glass with a coat of bees wax, or en- 
gravers' varnish. If wax is used, it must be spread over 
the surface as thin as possible. This is done by heating 
the glass over a lamp, and at the same time rubbing it with 
wax. A thin and even coat may thus be obtained. 

Next draw the design by cutting the wax with a sharp 
pointed instiTiment, quite down to the glass, so that every line 
may leave its surface naked; otherwise the design will be 
spoiled, since the acid will not act through the thinnest film 
of the wax. A large needle answers for a graver for this 
purpose. 

368. Having made the design, the etching is done by 
placing the glass in a horizontal position and pouring on the 
liquid acid. But a simple method is the temporary extrication 
of the gas from the fiuor spar, for the occasion. For this 
purpose, take a lead or tin cup, large enough to include the 
figures on the glass, the lower the better, and having placed 
on its bottom a table s])oonful of powdered spar, pour on it a 
quantity of strong sulphuric acid sufficient to form a paste. 
Then place the glass on the cup, as a cover, with the etching 
downwards, and set the cup in a dish of hot water, or apply 
to it the gentle heat of a lamp, taking care not to melt the 
wax. In twenty or thirty minutes the etching will be fin- 
ished, and the wax may be removed with a little spirit of 
turpentine. In this manner, figures of any kind may be 
permanently and beautifully done on glass. 

369. Since the above was written the composition and 
affinities of fluoric acid have been more minutely examined, 
and more appropriate names affixed to its compounds. 

Fluorine is the hypothetical base of the hydrofluoric acid. 
The latter is the present name of fluoric acid. Its compo- 
sition is 

1 eq. Fluorine, 184- 1 eq. Hydrogen, l=rl9. 

370. Fluohoric Acid. — A gas made by heating to redness 
a mixture of dry boracic acid, and powdered fluor spar. It 
is colorless, pungent, and produces a dense white cloud, 
when it escapes into a moist atmosphere. It is probably 
composed of 

1 eq. Boron, 20 + 6 eq. Fluorine, 108 = 128. 

Describe the method of making designs on glass. After the design is formed, 
in what manner is the etching done T AVhat is hydrofluorie acid ? What is 
the fluoboric acid ■? 



200 CARBON AND HYDROG ON. 

371. Fliiosilisic Acid. — A gas obtained from a mixture of 
fluor spar and silex by the aid of sulphuric acid. The fluo- 
ric acid produced in the usual way is a fluosilisic, since 
fluor spar nearly always contains more or less silex. Its 
composition is 

1 eq. Fluorine, 18+1 eq. Silicium, 8 = 26. 

COMBINATIONS OF SIMPLE NON-METALLIC COMBUS- 
TIBLES WITH EACH OTHER. 
CARBON AND HYDROGEN. 

CARBURETTED HYDROGEN, 8. 

1 eq. Carbon, 6+2 eq. Hydrogen, 2. 

LIGHT CARBURETTED HYDROGEN. 

372. This gas has also been called hydro-carburet^ and 
heavy injtammahle air. 

It exists in every stagnant pool of water, especially during 
the warm season, being generated by the decomposition of 
vegetable products. 

To obtain it from such places, fill a glass jar with water, 
and invert it in a stagnant pool or ditch ; then stir the mud 
under it with a stick, and the gas will rise and displace the 
water in the jar. To preserve it for examination, slide a dish 
under the mouth of the jar while in the water, and then 
carefully raise, and carry the whole to the place of experi- 
ment. 

The gas so obtained is found to contain a proportion of 
carbonic acid gas, which may be removed by passing it 
through lime water. 

This gas is composed by weight of 

1 equivalent of carbon, 6 

2 do. of hydrogen, 2 

8 

373. It is immediately destructive to animal life, and will 
not support combustion. It is highly inflammable, and 
burns with a yellowish blue flame, but owing to the carbon 
it contains, it gives considerably more light than pure hydro- 
gen. Mixed with atmospheric air, like hydrogen, it deto- 

What is fluosilisic acid? What are the names under which carhurelted 
hydrogen has been known ? In what place has this gas been formed by the 
Lvperation of nature ? How may it be obtained from stagnant pools of water . 
What gas is con.monly found mixed with this? What is the atomic com- 
position of carburetted hydrf^gen ? How does it effect animal life and com- 
•mstion ? 



CARBON AND HYDROGEN. 201 

nates po\\'erfully when inflamed. When burned with oxy 
gen, ihe product of the combustion is water and carbonic 
aciil. 

There appears to be several varieties of hght carburetted 
hydrogen, or perhaps the difference may depend on a mix- 
ture of the Hght and heavy kinds. If a volume of steam 
be sent through a red hot gun barrel filled with charcoal, the 
gas obtained differs little in its illuminating powers from 
that obtained from stagnant pools. Nor is there any mate- 
rial difference between these and that evolved by the burning 
of common wood, such as maple or beech, in a gun barrel. 
But if pine wood containing turpentine, be heated in the 
same manner, the gas obtained has much greater illumin- 
ating powers, the brilhancy of the flame being nearly equal 
to that of oil gas. Now, as by analysis there appears to be 
only two kinds, or varieties, of carburetted hydrogen; in the 
first of which there is but one proportion, and in the second 
two proportions of carbon, it is most probable that these dif- 
ferent powers of illumination depend on a mixture of the 
two gases. 

374. This gas sometimes exists in large quantities in coal 
mines, and is known by the miners under the name of fire- 
damp. The most shocking accidents have often occurred in 
consequence of the explosion of this gas in the mines, when 
mixed with atmospheric air. In some mines, this gas 
flows from the coal beds in vast quantities, being obviously 
the product of the decomposition of water by the coal. 
But in what manner the water is decomposed, is unex- 
plained. Did the process consist in the formation of sul- 
phuric acid, in consequence of the oxygenation of the 
sulphur, and the subsequent action of this acid on the iron 
of the sulphuret of iron, there would be formed sulphuretted. 
instead of carburetted hydrogen. 

There are no facts, it is believed, which warrant the sup- 
position, that in ordinary cases, the decomposition is conse- 
quent upon the heat, or ignition of the coal. Possibly in 
such vast bodies of coal as are found to exist in some mines, 
the water is slowly decomposed, by gradually imparting its 
oxj^gen to the carbon, without the aid of heat. 

When burned, why does this gas give a stronger light than pure hydrogen 
What is said concerning the several varieties of carburetted hydrogen 1 
Under what name is this gas known, when it occurs in coal mines ? In 
what manner is this gas formed in coal beds ? What are the remarks on 
this subject ? 

9* 



202 CARBON AND HYDROGEN. 

375. Explosive coTnpound. — Y\Q have already stated, that 
when carburetted hydrogen is mixed with atmospheric air 
and inflamed, a violent explosion is the consequence. In 
the coal mines of England, the mixture of atmospheric ail 
and the gas in question, often produces such an explosive 
compound. It appears that the miners have no certain 
means of ascertaining the presence of this gas, probably 
because, being much Hghter than the atmospheric air, it at 
first rises to the roof the mine, and then gradually descends 
towards the floor. As the miners work entirely by the 
hght of lamps, one of which is sufficient to set fire to the 
explosive compound existing throughout the whole cavern, 
it is obvious, that as soon as the hj^drogen has mixed with 
the air near the floor of the mine, in the exploding pro- 
portions, it must inevitably take fire. It can readily be 
imagined, particularly by those who have witnessed the 
detonation of a pint or two of this compound, that a 
quantity covering many acres of surface, and extending 
upwards in some places, at least, several hundred feet, 
must produce the most awful consequences. 

376. Explosion in Felling colliery. — Such explosions have 
often taken place in the coal-mines in different parts of 
England. That which happened in a mine called Felling 
colliery .^ in Northum.berland, on the 25th of May, 1812, was 
attended with the loss of 92 lives, and spread poverty and 
wretchedness throughout the whole district. Most of these 
men had wives and children, who depended entirelj^ on their 
daily labor for support, and who, in addition to the loss of 
their husbands and fathers, by so sudden and awful a death, 
were in a moment deprived of the means of subsistence. 

This mine had been wrought a century or more, and only 
a single accident from, fire-damp had before happened, and 
this was so trifling, as only to slightly burn two or three 
workmen. Twenty-five acres of coal had been excavated 
in this mine, and the number of men employed undei 
ground, at the time of the accident, was 128. The explo- 
sion took place between the hours of 11 and 12 in the 
morning. The fire was seen to issue from two shafts lead- 
mg to the mine, and called William and /o/m, and at the 



What is the consequence, when this gas is mixed with atmospheric air 
and inflamed ? In what situations is it said that explosive compounds are 
tnus formed? What is the reason that the miners are not aware of the exist- 
ence of this compound until the whole takes fire ? What number of lives 
were destroyed by such an explosion at Felling colherv. In 1812 ' 



CARBONS AND HYDROGEN. 203 

same instant, the noise of the explosion, which was heard 
three or four miles, and the trembhng of the earth, showed 
that an awful accident had happened there. 

The force of the expanded gas was such as to throw 
from the two shafts immense clouds of dust, and small coal, 
which rose high in the air, and also pieces of wood and 
working implements, which fell back near the shafts. As 
soon as the explosion was heard, the wives and children of 
the coUiers came bj hundreds to the place. But not a 
single person who was in the mine during the accident was 
to be seen. Terror and dismay was pictured on every 
countenance ; some were crying out for a father, some for 
a son, and others for a husband. 

377. The machinery for entering the mine, being shat- 
tered by the blast, it was at first impossible to go down, 
but the urgency of the occason soon impelled those present, 
to find the means of entering the shaft ; and in about half 
an hour from the time of the explosion, 32 persons, all who 
remained ahve out of 121, who were in the mine, were 
brought out. It appeared that of the whole number of the 
workmen, seven had come up, on different occasions, before 
the explosion, and were unhurt. The wives and children 
of those who were known to be still in the mine, waited 
in a most heart-rending state of anxiety, and those who had 
their friends restored, seemed to suffer nearly as much from 
excess of joj^, as they had before done from suspense and 
grief These hurried away with their friends from the 
dismal scene, while those who were still in suspense, or 
whose hopes ended in the dreadful certainty that their hus- 
bands or fathers were indeed among the dead, still lingered 
about the place, silently enduring the torture of a forlorn 
hope, and uttering cries of agony and despair. 

378. As the fate of many of the men was still uncertain, 
because they were in different parts of the mine from those 
who had been found ahve, the exertions of those above were 
unremitted, and in the course of an hour or two, many hun- 
dred people had collected around the shafts, all anxious to 
do every thing in their power for the sufferers. But it was 
soon found that the pit in some places was still on fire, the 
gas probably continuing to burn as it was extricated from 
the coal. It was also lound by those who attempted 
to descend, that where the mine was not on fire, it was 
filled with carbonic acid gas, the product of combustion, and 
that therefore it was impossible for any person to make fur- 



204 SAFETY LAMP 

:hor examination without inevitable death Conseqiieritlj 
ail nope of finding any of the unfortunate persons alive, who 
were still in the mine, was abandoned, and it was proposed 
that the shafts should bj closed, in order to extinguish the 
fire. But the wives and children of the sufferers, distracted 
at the idea of seeing their friends buried alive, and still en- 
tertaining hopes of their recovery, made the most pitiful 
importunities against such a course, while others became 
frantic with rage, and accused those of murder who propo- 
sed it. The owners of the mine, therefore, in mercy to the 
feelings of these distracted widows and orphans, waited 
until all were satisfied that no hopes remxained of ever aga"n 
seeing their friends alive, when the two shafts were closed 
with earth. 

379. To insure the extinguishment of the fire, the mine 
was kept closed from the 27th of May until the 8th of July, 
on which day it was again opened and ventilated. On this 
occasion, the lamentations of the widows and orphans were 
again renewed, and such was the crowd of people that 
assembled on the spot, some urged by feehng, and others by 
curiosity, that constables were in attendance to preserve 
order. Those who descended to search for the remams of 
these unfortunate sufferers, found no difficulty in breathing 
the air in the mine, but were struck w^ith horror at the scene 
of destruction and mutilation which the explosion had occa- 
sioned. 

The search continued until the 19th of September, when 
91 bodies had been found, brought up, and interred, but the 
92d never was found. 

We have been thus particular in describing a single 
instance of the awful effects of the fire-damp in mines, that 
the reader might fully appreciate the safety-lamp, an inven- 
tion made by Sir Humphrey Davy, expressly for the pur- 
pose of preventing such explosions, and which has proved 
completely successful. 

380. Invention of Safety Lamp. — Before the invention of 
this lamp, such explosions were more or less common, and 
all the mip'^s were subject to them, though none has been 
attended wuh such destruction to human life as that of 
Felling colliery. In 1815, such an occurrence happened in 
a mine at Durham, and destroyed 57 persons, and in another 
mine, 22 persons were killed in the same manner. 

Does it appear that all excavated coal mines are liable to such accidfints "? 
What other accidents of the same kind are noticed ? 



SAFETY LAMP. 205 

The invention of the safety-lamp was not owing- to acci- 
dent, but is the result of inquiries undertaken and pursued 
expressly for the purpose of protecting- the miners from such 
homble accidents as we have described above. 

Sir Humphrey Davy commenced his inquiries, by deter- 
mining the proportions in which carburetted hydrogen and 
atmospheric air, in mixture, produce explosions ; and found, 
that when the gas is mixed with three or four times its vol- 
ume of air, it does not explode at all. When mixed with 
five or six times its bulk of air, it detonates, feebly, but when 
the air is in the proportion of seven or eight times the bulk of 
the gas, the explosion is most powerful ; and with fourteen 
times its volume of air, it still explodes, though sHghtly. 
He also found that the strongest explosive mixture would 
not take fire when in contact with iron heated to redness, 
or even to whiteness; while the smallest point of flame, 
owing to its higher temperature, caused an instant explo- 
sion. 

381. But the most important step in this inquiry was 
deduced from the fact that flame cannot be communicated 
through a narrow tube. The fact itself was known before, 
but Sir H. Davy discovered, that the power of tubes, in this 
respect, is not necessarily connected with their lengths, and 
that a short one is as efficacious in preventing the transmis- 
sion of flame, as a long one, provided its aperture be reduced 
in proportion to its length. Pursuing this principle, he found 
that fine v/ire gauze, which may be considered as an assem- 
blage of exceedingly short tubes, was totally impermeable 
to flame ; and on making the experiment, it was found that 
a lighted lamp, when completely surrounded with such 
gauze, might be introduced into an explosive mixture, with- 
out setting it on fire. 

Thus, the means of preserving the miners, a most useful 
and laborious class of people, from the dreadful effects of 
the fire-damp, was at once developed. It only became 
necessary to surround their lamps with a fine net work of 
brass wire, to insure their safety from explosion. This 

Who invented the safety-lamp, which protects the miners from such acci- 
dents? Was this invention accidental, or was the safety-lamp the result of 
mcjuiry and experiment ? In what proportions did Sir H. Davy find that car- 
buretted hydrogen and common air exploded with the least force, and in what 
proportions with the greatest force ? What did Sir H. Davy discover in, 
respect to the communication of flame through narrow tubes? On pursuing 
this inquiry, what did Sir H. Davy discover with respect to wire gauze ■? 
On this principle, how was it discovered that the miners might be protected 
from explosions ? 



206 



SAFETY LAMP. 



Inmp also indicates the existence of danger ; for when the 
fire-damp in the mine is in a highly explosive state, it takes 
lire within the gauze, and burns there, while the light of ihe 
lamp itself is unseen. When the miners observe this indica- 
tion of danger, they instantly leave the mine ; for although 
the flame within the gauze will not communicate with the 
explosive mixture on the outside, while the gauze is entire, 
yet as a high degree of heat would be kept up by the 
combustion within the lamp, the wire would soon become 
oxidated, and perhaps fall in pieces, when an instant explo- 
sion would be the consequence. 

382. The safety lamp is repre- 
sented by Fig. 71. The cistern, a, 
holds the oil, and is in all respects a 
complete lamp, with a spout at the 
side, for feeding it. On the top of this 
is set the cylinder of wire gauze, 5, 
supported by three iron or brass rods, 
to which is connected the disc, or 
cover c, and to the cover, the ring, 
or handle by which the whole is car- 
ried. The drawing, </, is a piece of 
wire passing through a tube, showing 
the manner in which the lamp is trim- 
med, and the wick raised, without 
making any dangerous communica- 
tion between the outside and inside of the lamp, 
passes through the cistern containing the oil. 

383. The reason why the wire gauze obstructs the 
communication of flame is easily explained. We have 
already stated, that according to the experiments of Sir H. 
Davy, the heat of flame is greater than that of a metal 
heated to whiteness, for the former occasioned a mixture 
of air and gas instantly to explode, while the iron, though 
white hot, produced no effect. Now the metals are all 
rapid conductors of heat ; when, therefore, the flame comes 
in contact with the wire, its temperature is so reduced by 
the conducting power of the metal, as to be incapable of 
secting fire to the gas which is on the outside. Any one 
may illustrate this principle, by holding a piece of wire 




This tube 



In what manner do these lamps indicate the presence of danger? Why 
does it become necessary for the men to leave the mine, when the explosive 
mixture hums within the gauze ? Describe the safety lamp, as represented 
at Fig. 70, and point out the uses of its several parts. Explain the reajion 
why the flame is not communicated through the wire gauze. 



GAS LIGHTS. 207 

gauze over the flame of a lamp, and then bnnging his 
hand over this, as near the lamp as he can bear. Now on 
removmg the gauze, he will find that he cannot for an 
instant bear the additional heat. 

CARBURET OF HYDROGEN, 14. 

2 eq. Carbon, 12 + 2 eq. Hydrogen, 2. 

OLEFIANT GAS. 

■ 384. To prepare this gas, mix in a capacious tubulated 
retort, three measures of alcohol, with eight measures of 
undiluted sulphuric acid, and then apply the heat of a lamp. 
This mixture turns black, swells, and emits bubbles of gas 
in abundance, which may be collected over water, in the 
same manner as described for hydrogen. 

Alcohol is composed of carbon, hydrogen, and oxygen. 
During this process, the oxygen of the sulphuric acid 
appears to combine with a part of the carbon of the alcohol, 
in consequence of which, sulphurous acid gas is evolved, 
and the hydrogen is set free. At the same time, the hydro- 
gen combines with another portion of the carbon, and 
escapes in the form of bicarburetted hydrogen. Or perhaps 
the evolution of the defiant gas is owing to the strong 
attraction which the sulphuric acid has for the water which 
the alcohol contains, and by combining with which, the 
hydrogen and carbon are liberated. 

defiant gas is colorless and elastic. It possesses no 
taste, and when pure, httle smell, though, when not purified, 
it has a faint odor of ether. When mixed with oxygen and 
inflamed, it explodes with violence. 

This gas is a little fighter than atmospheric air, 100 cubic 
inches weighing 29.64 grains. The weight of carbon in 
this composition is 25.41 grains, and the weight of hydro- 
gen 3.23 grains. 

Olefiant gas, therefore, consists of 

Grains. 

Carbon, by weight, 24.31, or two atoms, 12 
Hydrogen, do. 4.23, or two atoms 2 

29.64 14 

How may this principle be illustrated by holding a piece of wire gauze 
and the hand over a candle ? How is olefiant or bicarburetted hydrogen gas 
obtained? What is the composition of alcohol? What are the chemical 
changes which take place during the production of olefiant gas? What arc 
the sensible properties of this gas ? Does it explode when mixed with oxygen 
and inflamed? What is the weight of carbon, and what the weight of hvdro 
gen, in this gas ? 



208 ^AS LIGHTS. 

This gas may be decomposed, by passing it through a 
red hot porcelain tube, one proportion of carbon being de- 
posited, in consequence of which it is converted into light 
carbuietted hydrogen, which, as we have already seen, 
contains only 1 proportion of carbon to 2 of hydrogen. 

GAS LIGHTS. 

385. The olefiant gas, when pure, (with perhaps a single 
exception) gives the most brilliant ai d intensely luminous . 
flame of any known substance. The illuminating powers 
of other gases depend chiefly, if not entirely, on the olefiant 
gas they contain. In all cases, the light of any inflamma- 
ble gas is in exact proportion to the quantity of carbon it 
contains. 

The flame of pure hydrogen scarcely gives sufficient light 
to show the hour on a watch dial. When combined with 
one proportion of carbon, forming carburetted hydrogen, its 
hght is greatly increased, and when combined with another 
proportion, its light becomes perfectly fitted for the purposes 
of illumination. 

386. Gas light, for the purpose of illumination, was first 
made and emploj^ed by Dr. Clayton, an Englishman, in 
1739, but from some unknown cause, was given up, and 
neglected for sixty years afterwards. At length, Mr. Mur- 
dock instituted a series of experiments on the subject, and 
the gas distilled from coal began to be used, on a small 
scale, for lighting different factories in the vicinity of London. 

From that period, which was about 30 years since, gas 
fights obtained from coal, or oil, have gradually come into 
use, for the purpose of fighting streets, shops, and manu- 
fiictories, in all parts of Great Britain, and is, at the present 
time, in common use on the continent of Europe, and in 
several parts of America. 

For many j^ears, the gas lights of London, and other parts 
of England, were suppfied entirely by the distillation of bitu- 
minous coal ; but more recently, many of the gas works, in 
different parts of that kingdom, obtain their fights from oil. 
In this country, also, oil gas is chiefly employed. 

What is the atomic composition, and what the combining nnmber of this 
gas? How is olefiant gas decomposed and resolved into carburetted hydrogen ? 
What is said of the brilliant light of the olefiant gas ? On what does the bril- 
liancy of gas lights depend ? When were gas lights, for the purpose of illumi- 
nation, first employed ? From what substance was gas lights first obtained? 
What is the substance now employed in this country, and in some parts ol 
Eng)and, for this purpose ? 



GAS LIGHTS 209 

387. In respect to the advantages of gas, on the morals 
of society, m great cities, Mr. Gray, in his Operative Ckevt- 
ist, saj's: "From the more brilhant manner in which our 
streets (those of London) are hghted by gas, than they ever 
were or could be, by oil or tallow, there is a greater degrf^e 
of security, both in person and property, for every class of 
honest men. Crimes cannot now be committed in darkness 
and secrecy; and as the risk of detection increases, the 
temptation to guilt is diminished, and thus coal gas, by the 
brilliant light it sheds on our streets, has worked, and is now 
working, a moral reformation. The house-breakers and 
pick-pockets dread the lamps more than the watchmen, and 
a more efficacious measure of police was never introduced 
into society, than that from gas lights." 

Oil gas is obtained by distilling impure whale or other oil, 
in large cylindrical cast iron retorts. From four to six such 
retorts, which, in appearance, resemble 24 pound cannon, 
are placed across a furnace built of brick, and are all heated 
by the same fire. These are half filled with pieces of brick, 
or iron, in order to increase the surface, and thus to effect 
the decomposition of a greater proportion of the oil. The 
oil is contained in a reservoir placed so high as to run to the 
retorts through a tube, of which each retort has a separate 
branch. The oil is admitted into the retorts on the outside 
of the furnace, the quantity being regulated by a stop-cock, 
with which each is furnished. On the opposite side of the 
furnace, the gas is conducted from each retort by separate 
tubes, which afterwards join in a common tube of larger 
size, and thence is conveyed to the gasometer. The oil is 
admitted into the retorts in a very small stream, or some- 
times only by drops, and is decomposed, and converted into 
gas as fast as it runs in. 

388. In large works, the gasometer is of immense size, 
being 30 or 40 feet in diameter, and 15 or 20 feet high, and 
capable of containing from 12 to 20,000 cubic feet of gas. 

This is made of sheet iron, suspended by a chain, over a 
pulley, and counterbalanced by weights on the other side. 
This falls into a tank, or cistern, held together by iron hoops, 
which are drawn with great force around it by means of 
screws. The tank beins: filled with water, the 



What is said of the influence of gas lights on the morals of London ? How 
is oil gas manufactured ? Describe the furnace and retorts. How is the oil 
admitted into the retorts ? In large works, what is the size of the gasometer 



210 ^AS LIGHTS. 

IS let down into it, while the air escapes by opening a valve 
in its top. When the air is all excluded, the gas is con- 
ducted into the gasometer by a pipe coming from the retorts, 
and opening under the water. As the gas rises through the 
water, the gasometer is buoyed up, and rises also, and thus 
the vessel is filled with inflammable gas instead of air. 

From the gasometer, which is the great fountain, the gas 
is conducted by one laige iron pipe, laid under ground to 
the place or street where it is burnt. It is then conducted 
in smaller pipes through the different streets, and from these 
pipes it is conveyed to the houses and shops by small lubes ; 
and tubes of still smaller size convey it to the burners where 
the lights are wanted. 

Rosin has lately been used instead of oil, and is said to 
yield a gas fully equal in quality to that of oil, and at a 
much less expense. 

As the burners are stationary, in the ordinary mode of 
lighting with gas, there exists an inconvenience in its em- 
ployment for the purpose of common household illumina- 
tion, where the hghts are often necessarily carried to 
different parts of a room, or from one room to another. There 
is also another inconvenience, which arises from the expense 
of laying conductors through streets where the houses are 
scattered, and consequently, where but a small quantity of 
the gas is wanted. To remedy these defects in the ordi- 
nary method of lighting with gas, it has, within a few years, 
been proposed to condense the gas in strong copper, or brass 
lamps, at the gas works, and then transport them, thus filled, 
to the houses, to supply the place of common lamps. This 
is distinguished by the name portable gas, and has been, and 
it is believed is still extensively employed in London and 
its vicinity. 

389. To fill these lamps, there is provided a long iron 
pipe, at one end of which is a forcing pump, which is also 
connected with another pipe leading from the gasometer to 
the pump through which the gas is conveyed. The long 
pipe is furnished with short tubes placed at convenient dis- 
tances apart, and communicating with its inside. These 
tubes are cut with screw threads, which fit the screws at 

How is the gas conveyed into the gasometer? How is the gas conveyed 
from the gasometers to the gas burners ? What inconvenience is expe- 
rienced in the use of ordinary gas lights ? How has it been proposed to remedy 
this defect ? Under what name is this condensed gas known ? In what 
manner are the portable gas lamps filled ? 



GAS LIGHTS 211 

the bottoms of the lamps, and on which these vessels are 
screwed, to be filled. Thus, hy working the forcing-pump, 
the g-as IS brought from the gasometer, forced into the pii'p, 
and from the pipe into the lamps, so that many are filled ut 
the same time. There is a mercurial gauge connected with 
the pump, hy which its pressure is shown, and consequently 
hy which the amount of condensation of the gas in the 
lamps is indicated. The flame, in burning the gas, is regu- 
lated by turning a small screw, and the gas is prevented 
from escape at the bottom by a vah^, and another screw. 

The gas obtained from oil is much purer than that ob- 
tained from coal. The latter cannot be burned until it is 
purified by being passed through lime water, in order to de- 
prive it of the carbonic acid, and other impurities ; but the 
oil gas does not require any such process, being fit for use 
as it passes from the retort. 

390. lire illuminating power of the oil gas is also much 
greater than that of coal gas. According to the experi- 
ments of Mr. Accum, two cubic feet of coal gas will burn 
one hour, and give a quantity of light equal to three tallow 
candles, eight of which weigh a pound. But according to 
the experiments of Mr. Dewey, superintendent of the gas 
works of New- York, one cubic foot of od gas will give light 
for one hour, equal to 8 candles, 6 to the pound. This 
agrees very nearly with the result of Mr. Ricardo's experi- 
ments, who found that a given quantity of oil gas was equal 
in illuminating power to four times the same quantity of 
coal gas. One gallon of clean whale oil will make 100 
cubic feet of gas, which, according to the above statement, 
will burn 100 hours, and give as much light as 8 mould 
candles, 6 weighing a pound. Such an immense diflference 
between the cost of gas, and other lights, would seem to in- 
dicate the propriety of establishing gas works in every 
village. But the expenses of erecting and tending small 
establishments of this kind, are such as not to yield any 
considerable profit to the owners. 



How is it ascertained with w-hat degree of force the gas is condensed in the 
lamjis? Which is most pure, the gas obtained from oil, or that from coal ? 
Which gas has the greatest illuminating power, that from the coal, or that 
from oil ? What is said to he the comparative difference between the 
illuminating power of coal and oil gas? What quantity' of gas is it said one 
gallon of oil will make, and how long will this gas burn ? The cost of oil gas 
bciug much less than other lights, why are they not universally used ? 



212 HYDROGEN AND SULPHUR. 



uyphogen and sulphur 

S LT LPH URETTED HYDROGEN, 17. 

1 eq. Sulphur, 16+1 eq. Hydrogen, 1. 

391. This gas may be procured by placing in a retort 
some sulphuret of antimony^ or iron, and pouring on it sul- 
phuric or muriatic acid. The sulphurets of these metals 
may be prepared \)y heating either of them, in filings or 
powder, with sulphur; or the natural sulphurets may be 
emploj^ed. The chemical changes, concerned in the for- 
mation of this gas, are as follows : The oxygen of the water 
which the acid contains unites with the metal of the sul- 
phuret, which metal is then dissolved by the acid. Thus, 
the hydrogen of the water, and the sulphur of the sulphuret, 
are both set at liberty, and having an affinity for each other, 
they combine, and escape in the form of sulphuretted 
hydrogen. 

Sulphuretted hydrogen is a transparent, elastic gas, which, 
both to the taste and smell, is exceedingly unpleasant and 
nauseous, its odor being similar to that of putrefying eggs. 
Under a pressure of 17 atmospheres, that is, under a weight 
equal to 255 pounds to the square inch, this gas is con- 
densed into a colorless liquid, but again assumes its gaseous 
form, when the pressure is removed. 

392. This gas is instantly fatal to animal life, when pure, 
and even w^hen diluted with 1500 times its bulk of air, has 
been found so poisonous as to destroy a bird in a few sec- 
onds. Like hydrogen, it instantly extinguishes flame, but 
is itself inflammable, and burns with a pale blue flame. 
The products of its combustion are water and sulphuric 
acid. The composition of this gas being hydrogen and sul- 
phur, the water formed during its combustion is the product 
of the union between the hydrogen and the oxj^gen of the 
atmosphere, during the act of combustion ; while the sul- 
phuric acid is foraied by the union of the oxygen of com- 
bustion with the sulphur. 

Sulphuretted hydrogen tarnishes silver, and even gold, 

How may sulphuretted hydrogen be procured? What chemical changes 
take place by which this gas is evolved ? What are the sensible properties 
of this gas? Under what pressure may this gas be condensed into a li(juid? 
Does it remain liquid when the pressure is removed? What is said of the 
poisonous eifects of this gas? What are the effects of plunging a burning 
candle into this gas ? When this gas is burned, what are the products of 
combustion ? Whence come the water and sulphuric acid ? 



HYDROGEN AND PHOSPHORUS 213 

and blackens paint made with preparations of lead. This 
gas is often generated during the decomposition of animal 
products, in sink drains and ditches, and hence the paint of 
white lead, about such places, often becomes black in con- 
sequence. Eggs contain a small quantity of sulphur, which, 
on boihng, is converted into sulphuretted hydrogen, and 
hence a silver spoon is instantly tarnished by coming in 
contact with a boiled egg. 

The composition of sulphuretted hydrogen by weight, is 
as follows : 

1 00 cubic inches of this gas weigh 36 grains. 

This is composed of sulphur, 33.89 do. 

do. do. of hydrogen, 2.11 do. 

36.00 

HYDROGEN AND PHOSPHORUS. 

PHOSPHURETTED HYDROGEN, 17. 

1 eq. Phosphorus, 16+1 eq. Hydrogen, 1. 

393. This compound consists of hydrogen, in which is 
dissolved a small quantity of phosphorus. It may be formed 
in several ways. One of the most simple is the following : 
Into five parts of water put 15 or 20 grains of phosphorus, 
cut into small pieces. It must be cut under water to pre- 
vent its taking fire. Then add one part of granulated zinc, 
and pour in three parts of sulphuric acid. 

The gas will instantly rise through the water in small 
bubbles, and will take fire spontaneously on coming in con- 
tact with the air. Each bubble as it takes fire will form a 
horizontal ring of white smoke, which will gradually en- 
large as it rises, until lost in the air. The cause of this 
curious appearance is owing to the formation of a small 
quantity of phosphoric acid by the combustion of the phos- 
phorus, and which, having a strong affinity for moisture, 
attracts it from the atmosphere, and thus forms a little ring 
of dew, which is visible to the eye. 

Phosphuretted hydrogen may also be obtained by placing 
some pieces of phosphuret of lime in water, when the gas 
will be extricated, and will rise through the water as above 
described. (See Phosphuret of Lime.) 

What is its effects on the metals ? What is the composition of 100 cul)ic 
inches of this gas by weight? How is phosphuretted hydrogen formed? 
What singular property does this gas possess ? How is the ring of white 
smoke accounted for, which rises after the combustion of a bubble of thisgas ' 



214 iNITROGEN AND CARBON. 

394. This gas detonates with great violence when mixerl 
witli oxygen, and forms a dangerous explosive compound 
with atmospheric air; consequently much caution is re- 
quired in making experiments with it. 

When a bubble of phosphuretted hydrogen is allowed to 
mix with oxygen, a flash of the most vivid hght is sponta- 
neously produced, which, in a darkened room, resembles 
lightning. The safest method of performing this beautiful 
experiment, is to let up into a small strong bell glass, or a 
thick glass tube, a few ounces of oxygen gas. Then, hav- 
ing collected a little of the phosphuretted hydrogen in a 
small vial, hold the bell glass in the left hand, with its 
mouth under water, and with the right hand manage the 
vial, so as to let only a single bubble at a time escape into 
the oxygen. The detonation of each bubble will produce a 
considerable reaction on the bell glass, which will be fek 
by the hand. But if the experiment be performed as de- 
scribed, there will be no danger of an explosion. 

The gas above described is called per-phosphuretted hy- 
drogen^ denoting, as already explained, the highest degree 
with which one body unites with another. It is so called 
to distinguish it from the proto-phosphuretted hydrogen^ which 
contains only half the quantity of phosphorus, and i: a 
much less interesting compound. 

Per-phosphuretted hydrogen consists of 

1 equivalent of phosphorus, 16 
1 do. hydrogen, 1 

17 

NITROGEN AND CARBON. 

CARBURET OF NITROGEN, 26. 

2 eq. Carbon, 12+1 eq. Nitrogen, 14. 

CYANOGEN. 

395. By boiling together red oxide of mercury and Prussian 
blue in powder, with a sufficient quantity of water, there 
may be obtained a compound which shoots into crystals, 
and which was formerly called prussiate of mercury^ but is 
now known by the name of cyanuret of mercury. 

With what substances does phosphuretted hydrogen afford dangerous de- 
tonating compounds ? What directions are given for admitting bubbles of 
this gas into oxygen? What is the equivalent composition of per-phosphu- 
retted hydrogen ? How may cyanuret of mercury be formed ? 



PRUSSIC ACID. 215 

When this salt is heated in a retort, it turns black, me 
cjanogen passes over in the form of a gas, and the mercury 
is revived, or assumes its metallic form. 

This gas has a pungent, disagreeable odor, burns with a 
purplish blue flame, extinguishes burning bodies, and is re- 
duced to a liquid under the pressure of about three and a 
half atmospheres. This gas must be collected over mercur3^ 

1 00 cubic inches of this gas weigh 55 grains, and is found 
to be composed of 

2 equivalents of carbon, 12 

1 do, nitrogen, 14 



26 its combining number. 

Cyanogen, though a compound gas, has the singular pro- 
perty of combining with other substances, in a manner per- 
fectly similar to the simple gases, such as oxygen and hydro- 
gen. ^ _ 

The term cyanogen comes from two Greek words, signi- 
fying to form hlue^ because it is an ingredient in Prussian 
blue. 

HYDROCYANIC ACID, 27. 

1 eq. Cyanogen, 26-t-l eq. Hydrogen, 1 

PRUSSIC ACID. 

396. Cyanogen is obtained by simply heating cyanuret, 
or prussiate of mercury, as above described. Hydrocyanic, 
or prussic acid, is composed of cyanogen and hydrogen. It 
may be obtained by heating in a retort a quantity of prus- 
siate of mercury v/ith two thirds of its weight of muriatic 
acid. During this process there takes place an interchange 
of elements. The cyanogen of the cyanuret of mercury 
unites with the hydrogen, forming hydrocyanic acid, while 
a muriate of the peroxide of mercury remains in the retort. 

But a more common method of making prussic acid is 
the following: 

397. Process for Prussic A cid. — Mix together, in a conve- 
nient vessel, four ounces of finely powdered Prussian blue, 

How is cyanr,?pn procured? What are the properties of this gas ? What 
is itie e(]aivalc. composition of this gas, and what is its coml)ining num- 
ber? Whence comes the name of this gas? How may hydrocyanic, or 
prussic acid, be formed by means of prussiate of mercury and muriatic acid? 
What are the int ■- ^changes of elements which take place during this proce.ss? 
What is the mor eommon method described for making prussic acid ^ 



216 



PRUSSIC ACID. 



Fig. 72. 



two and a half ounces of red oxide of mercury, and tweivc 
ounces of water. Boil the mixture for half an hour, now 
and then stirring it. The blue color will disappear, and the 
solution will become yellowish green. Filter the solution, 
and wash the residuum by pouring on boiling water, in 
quantities sufficient to make up the loss by evaporation, and 
let this also pass through the filter. 

Put this solution, which is a prussiate of mercury, into a 
retort containing two ounces of clean iron filings, then con- 
nect the retort with a receiver, and place them on a lamp 
furnace, as represented by Fig. 72, 
taking care that the juncture be made 
air tight, which may be done by wind- 
ing a wet rag around the neck of the 
retort. Next pour into the retort one 
ounce of sulphuric acid, diluted with 
three or four parts of water, and stop its 
tubulure by passing in a straight glass 
tube, which had been ready prepared by 
being passed through a cork. Then 
light the lamp, and distil with a slow 
heat, until three ounces of prussic acid 
is obtained. The receiver must be kept 
cold, and also from the Hght, by being 
covered with a wet cloth. 

The fumes of this acid are exceed- 
ingly poisonous, and therefore the lamp furnace should be 
set in a fire-place during the process, so that they may 
escape up the chimney. There is a comphcated interchange 
of principles which take place in this process, which Scheele 
explains thus. In Prussian blue the prussic acid exists in com- 
bination with iron. The red oxide of mercury having a stronger 
attraction for this acid than the iron has, the Prussian blue 
is decomposed, and a prussiate of mercury is formed, which 
is soluble in water. On the addition of the iron filings and sul- 
phuric acid to this solution, the iron absorbs the oxygen from 
the mercury, which is then precipitated in the metallic form, 
and at the same instant the iron is thus oxidized, it is dis- 
solved b}^ the sulphuric acid forming the sulphate of iron. 
Thus, the prussic acid is liberated, because it does not com- 




CS) 



What is said of the poisonous quality of the fumes of this acid, and of the 
precautions to avoid them ? Explain carefully the complicated interchange 
of chemical principles that takes place by this process. Wh .' is the apoear 
ance of the acid thus obtaint^d '^ 



PRUSSIC ACID 217 

bine with the metals, but only with their oxides, and as thf^ 
iron deprives the prussiate of mercury of its oxygen, tlic 
prussic acid remains free in the solution of the sulphate of 
iron, an ' being volatile, readily passes over into the receiver, 
by a gei tie heat. 

398. The hj^drocj^anic acid thus obtained, is a perfectly 
colorless, hmpid fluid, and cannot be distinguished by the 
eye from distilled water. It has a strong odor, resembling 
that of peach blossoms, and when much diluted has the 
taste of bitter almonds. 

399. A most deadly Poison. — Prussic acid is the most 
active and powerful of all knowai poisons. A single drop 
placed on the tongue of a dog causes his death in a few 
seconds, and a servant girl who swallowed a sm.all glass of 
it, diluted with alcohol, fell down instantly, as though struck 
w^ith apoplexj^, and died in two minutes. A professor at 
Vienna, having prepared some of this acid in its most con- 
centrated state, by w^ay of experiment, diffused some of it on 
his naked arm, and was killed thereby in a short time. 

These instances not only show the terrific and mysterious 
effect which this substance has on the animal economy, but 
they also show w'hat extreme caution is necessary in prepar- 
ing and using it. When much diluted, it has, however, been 
considerably employed as a m.edicine, in cases of consump- 
tion, and often w^ith good effect. 

400. Although the investigations of chemistry have devel- 
oped this substance, than which, even lightning itself is 
scarcely more prompt, or sure, in destruction, still the wis- 
dom of Omniscience has connected circumstances with its 
production and nature, which, in a great measure, will always 
prevent its employment for criminal purposes. The process 
by which it is made, requires more chemical skill than gen- 
erally falls to the lot of unprincipled and vicious persons; 
and when obtained, its active properties are so evanescent, 
as never to remain more than a week or tv/o, without pecuHar 
treatment, and sometimes it becomes nearly inert in a few 
days. The odor, also, which is distinguished in animals 
destroyed by it, is often the sure means of detection. 

The commencement of its decomposition is marked by the 

What is the smell of this acid? What casps are mentioned of its poi.sonrus 
effects ? For what purposes is this acid employed when much diluted ? V, hat 
circumstances are connected with the production and nature of this acid 
which it is said will prevent its employment for wicked purposes ? 

10 



218 PRUSSIC ACID. 

reddish brown color of the Hquid, and, in a short time after, 
it becomes black, and deposits a thick carbonaceous sub- 
stance, at the same time it loses its peculiar smell, and emits 
that of ammonia. In this state, the prussic acid has none 
ot Its former properties, but becomes entirely inert and 
worthless. 

This substance possesses the sensible qualities of an acid 
only in a very slight degree, being hardly sour to the taste, 
and producing but verj^ little change in the blue colors of 
vegetables. It however performs the office of an acid in 
combining with alkahne bases, forming salts, called prussi- 
ates^ or hydrocyanates. 

401. The following is an example, by which the compo- 
sition of a substance may be found, when one of its elements 
can be made to combine with a third body, in a known pro- 
portion. B}^ a previous experiment it was ascertained how 
much cyanogen would combine with a given proportion of 
potassium, the basis of potash. Then, Gay Lussac expo- 
sed to the action of 100 measures of prussic acid, heated so 
as to be in a state of vapor, a quantity of potassium pre- 
cisely sufficient to absorb 50 measures of cyanogen. By 
this process, cyanuret of potassium was formed, and exactly 
50 measures of the vapor of prassic acid was absorbedj 
leaving 50 measures of pure hydrogen remaining in the ves- 
sel in which the experiment was made. 

From this experiment, it appears that prussic acid is com- 
posed of equal volumes of cyanogen and hydrogen, and 
therefore that they combine in the ratio of their specific gravi- 
ties, that is, the weight of the vapor of pmssic acid must be 
the combined weights of cyanogen and hydrogen, of an 
equal bulk. 

402. Now the specific gravity of hydrogen is known to 
be 0.0694, and cyanogen gas, 1.8044, air being 1000. Cya- 
nogen, therefore, is 26 times as heavy, bulk for bulk, as 

How does the acid appear while decomposing 1 Does this substance pos- 
sess the sensible qualities of an acid? Inwhat respect does it perform the 
office of an acid? How did Gay Lussac know that exactly 50 measures of 
cyanogen were absorbed by the potassium ? [Cyanogen combines with met- 
als in the same manner that oxygen does. See Cyanogen.] What was ll c 
quantity of hydrogen which remained after this absorption ? From this exper- 
iment, what appears to be the composition of prussic acid, by volume : and 
therefore, the vapor of prussic acid consists of the combined weight of 
what? How does it appear that cyanogen is 26 times as heai-y as hydroi^en? 
[Multiply 0.0694 by 26.] How does it appear that an atom of cyanogen is 
26 times as heavy as one of hydrogen ? [Because they combine in equal vd 
umes, but cyanogen weighs 26 times the most.] 



UARBOr^f AND SULPHUR. 219 

liydrogeri, and since they combine in equal proportions, bj 
volume, t3 form prussic acid, it follows that this acid con- 
sists of an atom of hj^drogen united to an atom of cyano- 
gen, and, therefore, that an atom of cyanogen gas is 26 
times as heavy as an atom of hydrogen. Thus, the atomic 
weight of cyanogen is 26, that of hydrogen being 1 , and the 
specific gravity of the vapor of prussic acid being the me- 
dium between them, is 0.9369, because 0.0694, the specific 
gravity of hydrogen, added to 1.8044, the specific gravity 
of cj^anogen, makes 1.8738, the medium or half of which is 
0.9369, the specific gravity of the vapor of prussic acid. 

The composition of prussic acid may therefore be stated 
thus: 

By volume. By weight. 

Cyanogen 50 1.8044 26, one atom, 

Hydrogen 50 0.0694 1, one atom. 

100 acid vapor. 27 atomic weight. 

Thus the atomic weight, or equivalent number for cyano- 
gen is 26, and that for prussic acid is 27. 

The above will serve as a practical example of the method 
of finding the atomic weight c f a constituent, under similar 
circumstances. 

CARBON AND SULPHUR. 

SULPHURET OF C A E, B O N , 3 8 . 

1 eq. Carbon, 6 + 2 eq. Sulphur, 32. 

403. This singular ^ and interesting compound, as the 
name indicates, is composed of sulphur and carbon. These 
substances unite only in one proportion ; by merely heating 
them together, no combination takes place, the sulphur 
burns away, or passes off in vapor, and the charcoal remains 
unchanged ; but by bringing the vapor of sulphur into con 
tact with charcoal at a red heat, the combination takes 
place immediately. For this purpose a porcelain tube is 
sometimes employed, but one of cast iron, or a gun barrel, 
coated with clay on the inside, is better. For this purpose, 
the clay is formed into a thin paste, with water, and poured 
into the tube, this being at the same time rolled so that the 

What then is the weight of an atom of cyanogen, that of hydrogen being 1 ? 
What is the specific gravity of the vapor of prussic acid, it being the medium 
between those of cyanogen and hydrogen ? From these data, what is the com- 
position of prussic acid, by volume and weight ? What is the equiyalent 
number for prussic acid? 



220 



CARBON AM) SULPHUR. 



cln V will cover every part. After one coat is applied, and 
(iru'd, by heating the tube, the same process is repeated, 
until the surface is well covered, and the iron is thus pro- 
tected from the action of the sulphur. If the tube is not 
well prpi)ared, the experiment will fail entirely, since the 
action of the sulphur in a few moments would destroy the 
iron. 

404. The tube, well covered, is filled with burning char- 
coal and laid in the furnace, Fig. 73j until it attams a white 
heat. The end, 

6, of the tube is Fis 

closed with a 
piece of clay, 
anil at a there is 
an aperture for 
the admission 
of the sulphur; 
this is also fur- 
nished with a 

a stopper of clay. A long glass tube, o, is attached to 
the iron pipe at c, and pass-^s into the capacious flask, /, 
through an aperture in the side. In the absence of such 
a flask, a double necked bottle will do. A waste pipe, 
m, arises from the flask, and leads into the open air through 
a window, so as to avoid the fumes of the sulphur. At 
the bottom of the flask some w^ater is placed, to receive 
the product of the experiment. The flask and glass tube 
should be kept cold during the whole process. For this 
purpose, the tube should be surrounded by a cloth kept wet 

e, and the flask suiTounded with 




with water from the cistern, 



When the apparatus is ready, and the iron tube is at a 
white heat, the stopper a is to be removed, and pieces of 
sulphur dropped in, and the stopper instantly returned to 
its place. The sulphur instantly melts, and in passing 
through the hot tube, which is a little inclined, is converted 
into vapor, and at the same time unites with the charcoal, 
to form the compound in question. 

The sulphuret of carbon, being condensed by the cold 
tube, flow^s along into the flask, and sinks in the water it 
contains. 

405. A more simple method of producing the sulphuret 
of carbon, where it is designed to make it in quantities, is 
the following: 



CARBON AND SULPHUR. 221 

A cast iron cylinder is procured, having a cover throiijrh 
which pass the tubes 5, c, Fig. 74. The cj^hnder is to be 
coated with clay in the manner above described for the iron 
tube, and then filled with charcoal, the tube 6, being in its 
place as shown by the figure. The cylinder is then to bo 
placed in a furnace, and heated to redness, and then the 

Fig. 74. 




sulphur introduced through the tube, J, the aperture of 
which must be immediately closed. The melted sulphur, 
passing down the tube to the bottom of the cylinder, is 
there converted into vapor, and passing through the ignited 
charcoal combines with it, and rises by the iron tube c, into 
the glass tube, e, along which it is condensed. The tube d 
leads from a cistern (^^ water, which is allowed in small 
quantities to run in a tl _ agh containing the glass tube, and 
from which it is conducted by the string A, to the dish x. 
The sulphuret as it is formed, passes down the tube /into 
the vessel w, this being half filled with pounded ice. The 
waste pipe w, conducts away any superfluous gas which is 
generated during the process. 

Whenever all is prepared, as above described, the intro- 
duction of smah quantities of sulphur by the tube b, will 
insure the production of the compound in question, so long 
as any charcoal remains in the cyhnder. It is apt, how- 
ever, to contain some impurities, and must be distilled with 
chloride of calcium. 

406. Pure sulphuret of carbon is transparent and color- 
less, and insoluble in water. It has a strong, disagreeable 
smell, pecuhar to itself, and is soluble in alcohol, and ether 
Its specific gravity is 1.272, and it boils at 127°, evapora- 
ting very rapidly during the process. Its freezing point is 



'Zti2 



METALS. 



60° below zero. In the open air, it is exceedingly volatile, 
and the cold it thus produces is intense. Under the ex- 
hausted receiver of the air pump, the evaporation of course 
is still more rapid. In this situation, a thermometer bulb, 
covered with fine lint, and moistened with this fluid, carried 
off the heat so rapidly by evaporation, that the mercury 
was frozen in the tube, and on substituting an alcohol 
instrument, the fluid sunk down to 80° below zero. Sul- 
phuret of carbon is soluble in fixed and volatile oils, and it 
dissolves camphor, phosphorus and sulphur. When the 
two latter substances are dissolved in it separatelj^, the 
evaporation of the fluid causes crystals of them, of remarka- 
ble regularity and beauty, to be deposited. 

Pvl E T A L S . 



407. 



TABLS OK THE DISCOVERY OF THE METALI 



NAMES OF METALS. 

Gold . . . 
Silver . . . 
Iron , . . 
Copper . . 
Mercury . . 
Lead . . . 
Tin ... . 
Antimony 
Bismuth . . 
Zinc. . . . 
Arsenic . . 
Cobalt . . , 
Platinum . . 
Nickel . . . 
Manganese . 
Tungsten . . 
Tellurium , 
Molybdenum 
Uranium . , 
Titanum . . 
Chromium . 
Columbium 
Palladium 
Rhodium . 
Iridium 
Osmium . 
Cerium . 
Potassium 
Sodium . 
Barium . 
Strontium 
Calcium . 
Cadmium. 



AUTHORS OF TIIE DISCOVERY. 



■} 



Known to the ancients. 



Described by Basil Valentine 1490 

Described by Agricola • . . 1530 

First noted by Paracelsus .... 16th century. 

Brandt, the chemist '. . . , 1733 

"Wood, assay-master, Jamaica 1741 

Cronsted 1751 

Gahn and Scheele • " . . 1774 

Dr. Elhuyart 1781 

Muller 1782 

Heilm 1782 

Klaproth 1789 

Gregor 1791 

Vauguelin 1797 

Hatchett 1802 

Wollaston 1803 

Descotils and Tennant 1803 

Smiihson Tennant 1803 

Kissinger and Berzelius 1804 

Sir Humphrey Davy 1807 

Slromycr 1818 



M KTALS. 223 

I'ABLE Of THE DISCOVERY OF THE METAL S— Concluded. 
J»A.MES OF METALS. AUTHORS OF THE DISCOVERY. DJlTKS. 

Lithium . . ArlVedson , . . . . 1818 

Zirconiam . Berzelius 1824 

Alaniinuni . ) 

Gluciniun . > Wohler 1828 

Yttrium . . ) 

Tiiorium . . Berzelius 1829 

Magnesium . Bussy 1829 

Vanadium , Sefstrom 1830 

Lanthanum . Mosander 1839 

GENERAL PROPERTIES OF THE METALS. 

408. The metals form the most numerous class of unde- 
composed, or elementary bodies. They possess a peculiar 
lustre, called the metallic^ which continues in the streak, or 
when they are reduced to small fragments. They are all 
conductors of electricity and caloric. They are fusible, at 
diiferent temperatures, and in fusion retain their lustre and 
opacity. They are, in general, good reflectors of light, and 
with the exception of gold, which, in the thinnest leaves 
transmits a green hght, they are perfectly opaque. 

Many of the metals may be extended under the hammer, 
and are hence called malleahle, or under the rolling press, 
and are called lammable, or may be drawn into wire, and are 
called ductile. Others can neither be drawn into wire, nor 
hammered into plates, but may be ground to powder in a 
mortar; these are called brittle metals. 

The metals are capable of combining with each other, in 
any proportion, when melted together, and such compounds 
are called alloys. 

With a few exceptions, the metals have the greatest spe- 
cific gravity of all bodies. Potassium and sodium swim on 
water, but with these exceptions, the lightest among them, 
cerium, is about 5^ times the weight of water ; platinum is 
more than 20 times heavier than the same bulk of water. 

The metals differ in respect to brilhancy, color, density, 
hardness, elasticity, ductility, tenacity, conductility for ca- 
loric and electricity, fusibihty, expansibility by heat, stabihty, 
odor, and taste. 

409. Metals positive electrics. — When combined with 

Have any of the metals been decomposed? What is the peculiar lustre 
of the metals called? What imponderable agents do all the metals conduct? 
Are all the metals opaque? What are malleable, laminable, and ductile 
metals ? What are brittle metals ? What is an alloy ? What is said of the 
specific gravity of the metals ? What are the properties in respect to which 
the metals differ ? What is the electrical state of tlie raetals ^ 



224 MVTALS. 

oxygen, chlorine, iodine, or sulphur, and the resulting corn 
pounds submitted to the action of galvanism, the metals 
without exception are revived, and appear at the negative 
side of the battery, hence all the metals are positive electrics. 
The malleable metals, such as gold, silver, and iron, in 
whatever manner their surfaces are increased, if this is done 
rapidly, grow hot, and crumble under the hammer, or press, 
and finally refuse to be extended any further. It then be- 
comes necessary, if their surfaces are to be farther extended, 
to anneal them, which is done by exposure to a red heat, 
when they become soft and malleable as before. It is pro 
bable that this change is produced by a quantity of caloric 
which the metal retains in its latent state, and by which its 
particles are prevented from forming so compact a mass as 
before. When the metal is again drawn under the hammer, 
or press, it grows hot, and at the same time is increased in 
density and specific gravity, the caloric before absorbed 
being given out, and the metal is again rendered brittle 
by the process. 

410. All the metals become fluid hij heat. — All the metals 
are converted into a fluid state by sufficient degrees of heat. 
In this respect there is a vast difference in the different 
metals. Mercury is a fluid at all common temperatures, 
and does not assume the solid form unless exposed to a tem- 
perature nearly 40° below the freezing point, while platina 
and columbium continue solid under the highest heat of a 
smith's forge, and only become fluid under the heat of the 
compound blowpipe, or the action of the most powerful gal- 
vanic battery. 

411. Metals become oxides. — With several exceptions, 
these bodies suffer a singular change on exposure to air and 
moisture, or on exposure to air and heat. They lose their 
tenacity, brilliancy, and other qualities peculiar to the metals, 
soil the fingers, and cmmble to powder, but at the same 
time increase in weight. This change is termed oxidation^ 
and in this state they are termed metallic oxides. 

When the surfaces of the malleable metals are sudflenly increased, what 
effect is thereby produced on their temperature? When is it necessary to 
anneal a metal? How is the process of annealing supposed to affect the 
metal, so as to restore its malleability? By what means may all the metals 
be rendered fluid? What is said of the different temperatures at which the 
metals become fluid? The metals, with the exception of platina, gold, and 
silver, are said to suffer a peculiar change, when exposed to heat, or to 
air and moisture ? To what is this change owing, si^d what are the resulting 
compounds called ? 



METALS. 225 

This increase in weight and loss of metaUic splendor, 
does not happen when the metal is placed in a vacuum, or 
when ii is protected from the air by varnish or other means, 
but is found to be the consequence of the union between tho 
metal and the oxygen of the air, or water, or both. I'hus, 
iron, when exposed to air and moisture, spontaneously ab- 
sorbs oxygen, and is converted into a brown friable matter 
called rust. This is an oxide of iron. The increase ot 
weight is caused by the solid oxygen which thus combines 
with the metal. 

412. The metals combustibles. — Metals, in the language 
of chemistry, are termed combustibles^ because they are ca- 
pable of combining with oxygen, and thus passing througli 
the process of oxidation, or combustion. In ordinary com- 
bustion there is an extrication of heat and light, and under 
favorable circumstances, several of the metals exhibit these 
phenomena. Zinc burns with a brilhant flame when heated, 
and exposed to the open air; and iron, when heated in oxy- 
gen gas, emits the most vivid scintillations, attended with 
intense heat. Gold and platina, the metals which have the 
least afhnitj^ for oxygen, are still capable of uniting with it 
so rapidlj^, as to produce scintillations when heated with the 
flame of the compound blowpipe. In all cases the metals 
combine with oxygen most rapidly when exposed to the 
highest degrees of heat. Hence, at common temperatures, 
their oxidation proceeds so slowly as not to emit sensible 
light or heat ; and some of them, such as gold, silver, and 
platina, do not combine with it at all at such temperatures. 

Some of the metals combine with oxygen in only one pro- 
portion, while others combine with it in three or four pro- 
portions. Thus, there is only a single oxide of zinc, but 
there are three or four oxides of iron. 

413. Reduction of the metals. — After the metals are con- 
verted into oxides, they may again be reduced^ that is, 
brought back to their m.etallic states, by depriving them of 
their oxygen. This may be done by several methods, de- 

What causes iron and other metals to rust, when exposed to the air? Why- 
are the metals termed combustible in the language of chemistry ? Under 
what circumstances do several of the metals exhibit the ordinary phenomena 
of combustion? Under what circumstances do all the metals combine most 
rapidly with oxygen I What metals do not combine at all with oxygen at 
common temperatures ? Do the metate all combine with the same pro[)ortion 
of oxygen ? After a metal has been converted into an oxide, how may it again 
be reduced, or brought again to its metallic state ? By what method can the 
metals be deprived of their oxygen ? 

10* 



226 METALS. 

pending on the nature of the metal, or the force bj which it 
retains the oxjgen. The reduction of many of the metals 
from their ores, is nothing more than depriving them of theur 
oxygen. 

For this purpose, a common method is to heat the oxide 
\,vith some combustible which has a stronger affinity for the 
oxygen than the metal has. Thus, the oxide parts with its 
oxj'gen, and assumes the metallic form, while the combus- 
tible absorbs that which the oxide before contained, and is 
itself consumed, or converted into an oxide. As an exam- 
ple, carbon, when heated, has a stronger affinity for oxygen 
than iron, and therefore, when carbon and oxide of iron are 
strongly heated together, the iron is reduced while the char- 
coal is converted into an oxide, or an acid, and passes away 
into the air, or in common la,nguage, is burned up. This is 
the method of reducing iron from its ores. 

In some instances, heat alone drives away the oxygen 
and reduces the metal ; but in such cases the metal has only 
a weak affinity for oxygen. The oxides of gold, mercury, 
and platina, are thus reduced. 

*' Metals having stronger affinities for oxygen, resist such 
methods of reduction, and require the more powerful agency 
of galvanism. When metallic oxides are exposed to this 
influence, the reduced metal is found at the negative side of 
the battery, while the oxj^gen rises through the water at the 
positive side. 

414. The metals not soluble in their metallic state. — None 
of the metals are soluble in an a,cid, in their metalHc states, 
but when first combined with oxygen they are readily dis- 
solved. Gold will not dissolve in muriatic acid alone, be- 
cause this acid does not part with its oxygen with such 
facility as to form an oxide of the metal. But if a quantity 
of nitric acid be added to the muriatic, the gold instantly be- 
gins to enter into solution, and a chloride of the metal is 
formed. If a piece of zinc be thrown into sulphuric acid, it 
will remain undissolved, but if three or four parts of water 
be poured in, the metal is attacked with great violence, and 

What is one of the most common methods of reducing iron from its ores ? 
When iron is reduced by heating its oxide with charcoal, what becomes of 
the oxj'gen? In what instances does heat alone reduce the metallic oxides? 
VvHien metallic oxides are reduced by means of galvanism, at which pole of 
the batteiy is the oxygen extricated? * Are any of the metals soluble in the 
acids, w^hile in their metallic states? Why is it necessary to add nitric acid 
to the muriatic acid before it will dissolve gold? Why does not zinc dissolve 
in strong sulphuric acid '' 



METALS. 227 

soon dissolved. In this case the water furnishes the oxy- 
gen, by which the zinc is oxydized, and it is then dissolved 
by the acid. By this method hydrogen is obtained; the 
metal decomposing the water by absorbing its oxygen, while 
the hydrogen is set at liberty. 

The metals combine with phosphorus, sulphur, and car- 
bon, forming compounds called phosphurets, sidphurets, and 
carburets. 

415. Combination with sulphur. — Of all the inflammable 
bases, sulphur appears to possess the strongest aflinity for 
the metals, and its combination with some of them is at- 
tended with remarkable phenomena. This affinity is shown 
by the following interesting experiment. Introduce into a 
Florence flask, three parts of iron, or copper filings, and one 
part flowers of sulphur, well mixed together. Then stop 
the flask with a cork, and place it over a lamp, so as to heat 
it slowly, and as soon as any redness appears, remove the 
flask from the fire. The chemical action thus begun, will 
be continued by the heat evolved by the combination be- 
tween the sulphur and the metal, and the whole mass in 
succession will become red hot, which, in the dark, will 
produce a very beautiful appearance. 

We have stated, in a former part of this work, that when 
bodies pass from a rarer to a denser state, caloric is evolved. 

The heat and light, in this experiment, seems to be the 
consequence of this general law of condensation, for the sul- 
phuret, formed by the union of the two bodies, occupies 
much less space than the metal and sulphur did before. 

416. Many of the metallic sulphurets are very abundant 
in nature, forming the ores of the metals. Several metals 
are extracted entirely from such ores. The most abundant 
sulphurets are those of lead, antimony, copper, iron, and 
zinc. 

The phosphurets are seldom found as natural products, 
but may be foimed, by bringing phosphorus into contact 
with the metal, at a high temperature. 

Why is hydrogen evolved vt-hen the zinc is dissolved in diluted sulphuric 
acid ? When a metal combines with phosphorus, what is the resulting com- 
pound called ? What is the composition of a sulphuret ? What is the com- 
position of a carburet? What combustible body appears to possess the 
strongest affinity for the metals ? What experiment is stated, illustrating '.he 
affinity between iron and sulphur? Whence does the heat arise in this ex* 
periment? What are the most abundant sulphurets in nature? Are the 
%osphurets often found native ? 



22S METALS, 

Carbon unites with iron in several proportions. Unre* 
fine. I iron, steel, and black lead, are all carburets of iron, 
the latter containing 95 per cent, of carbon. 

417. Metallic salts. — When the oxide of a metal is dis- 
solved in an acid, there is a compound formed, which differs 
enthelj from either of these two substances, and when tJie 
liquor is evaporated there remains a crj^staliine solid, called 
a metallic salt. These salts differ materially from each 
other, according to the kind of acid and metal of which they 
are composed. Some of them, such as the sulphate of iron, 
and acetate of lead, are of great importance to the arts. 

The oxides of the metals readily unite, by fusion, with 
glass, and it is by such means that this substance is made 
to resemble gems and precious stones. The stained glass, 
so celebrated among the ancients, and used in the windows 
of churches, was prepared in this manner. This art was 
said to have been lost, but stained glass is still made in 
many parts of Europe, and in this country. [See Glass.) 

418. Alloys of the metals. — Compounds, made by fusing 
two or more metals together, are called alloys. In these 
cases there is a chemical union between the metals ; and 
hence such compounds differ greatly from the metals of 
which they are composed. In general, the specific gravity 
of the alloy is greater than the medium specific gravity of 
the two metals, and of consequence, the bulk of the alloy is 
less than that of the two metals taken separately. As an 
example, if two bullets of copper and two of tin, of equal 
bulk, be melted together, they will form little more than 
three bullets of the sam.e size. This diminution of bulk is 
accounted for, by supposing that the particles of the two 
metals enter into a closer union with each other, when com 
bined, than those of either did in a separate state. 

The alloys of the metals are also more easily fusible than 
the metals of which they are composed ; that is, the melting 
point of an alloy is below the medium temperature at which 
the metals crmposing it are fusible. 

419. Fvsihle alloy. — An alloy, made of 8 parts bismuth. 
5 lead, and 3 tin, is a curious instance of this fact. In a 

Wh;it carburets are mentioned? What is a metallic salt? What par 
ticular salts are mentioned, as being of great importance to the arts? What 
is said of the union between the metallic oxides and glass ? Wliat are alloys ? 
In what respect do alloys differ from the metals of which they are composed ? 
How is the increased specific gravity of the alloys accounted for? What is 
8a>d of the fusibility of alloys ? 



METALS. 229 

separate state, the melting point of lead is 500°, bismuth 
490°, and tin 430°, and jet, when these are fused together, 
the compound melts at 212°. Amusing toys, in the form 
of tea-spoons, have been made of this alloy. Such spoons, 
in the hand of those who know nothing of their composition, 
have excited great astonishment, by coming out of a cup of 
hot tea with their bowls melted oif. 

The number of metals, and the variety of properties 
which they possess, render it necessary to throw them into 
classes and orders, that a knowledge of these properties may 
be more easily obtained. 

CLASSIFICATION OF THE METALS. 

420. The following arrangement is that originally pro- 
posed by Thenard, and adopted by Henry and others. 

We have already stated, that some of the metals are re- 
duced from the state of oxides by heat alone, such metals 
having only a shght affinity for oxygen. Others, it was 
also stated, have so strong an attraction for oxygen, that they 
cannot be reduced by this method, but require the presence 
of a combustible, or some other means, for their reduction. 
The arrangement into classes is founded on this distinctive 
difference. The orders of the second class are founded on 
the powers of the metals to decompose water. 

CLASS I. 

Metals^ the oxides of which are reducible to the metallic state^ 
hy heat alone. These are 

Mercury, Platinum, Osmium 

Silver, Palladium, and 

Gold, Rhodium, Iridium. 

CLASS II. 

Metals^ the oxides of which are not reducible to the metallic 
state hy the action of heat alone. 

Order 1. — Metals which decompose water at common tern- 
peratures. These are 

Potassium, Lithium, Strontium, 

Sodium, Barium, Calcium. 



What curious illustration of the fusibility of an alloy made of bismuth, 
lead, and tin. is given ? What is the distinctive difference between the 
metals, on which is founded the arrangement into classes ? What are the 
peculiar properties on which the orders of the second class are founded? 



230 



MERCURY. 



Order 2. — Metals which are analogous to Order 1. The_> 
are the metallic bases of the earths. These are 

Magnesium, Yttrium, Zirconium, 

Glucinum, Aluminum, Silicium. 

Order 3. — Metals which decompose water at a red heal. 
These are 



Manganese, 

Zinc, 

Cobalt, 

Order. 4. 
temperature. 

Arsenic, 

Molybdenum 

Chromium, 

Tungsten, 

Antimony, 



Iron, 
Tin, 
Nickel, 



and 

Cadmium. 



—Metals which do not decompose water at any 
These are 



Uranium, 

Columbium, 

Vanadium, 

Lantanum, 

Cerium, 



Titanium, 

Bismuth, 

Copper, 

Tellurium, 

Lead. 



Of the first class, there are 8 metals ; of the second, there 
are 34, making 42 in all. 



421. Metals, the oxides of which are decomposed by the action 
of heat alone. 

MERCURY. 

Equivalent, 200. 

422. Mercury, or quicksilver, is found native, or in its 
pure state, only in small quantities, the mercury of com- 
merce being chiefly extracted from cinnabar, which is a sul- 
phuret of the metal. The metal is extracted from this ore, 
by heating it in iron retorts, mixed with iron fihngs, or lime. 
By this process, the sulphur combines with the lime, or iron, 
forming a sulphuret of lime, or iron, while the mercury is 
volatilized, and is distilled into a receiver, where it condenses 
in its pure form. 

This metal is distinguished from all others by preser^ang 



How are the classes and orders defined, and what are the names of the 
metals belonging to each? How many metals belong to the first class, and 
how many to the second ? What is the definition of class first ? From what 
substance is the mercuiy of commerce extracted? What is the composition 
of cinnabar, and what its chemical name? What is the method of obtaining 
the mercury from its sulphuret ? What striking distinction is there between 
raercuiy and other metals ? 



MERCURY. 23 1 

its fluidity at common temperatm'es. Its specific gravity is 
13.5. At the tem.peratiire of 660° it boils, rises in vapor, 
and may be distilled from one vessel into another. At 40'^ 
below zero it becomes solid, and is then malleable, and may 
be hammered into thin plates. 

When pm'e, this metal is not readily oxidized in the open 
air at common temperatures, but when mixed with other 
metals, such as tin, or zinc, there is commonly a film of 
oxide on its surface ; hence, this is an indication that the mer- 
cury is impure. When mercury is triturated with an equal 
quantity of sulphur, there is formed a black powder, called 
ethiops mineral. 

423. Mercury readily combines with gold, silver, tin, bis- 
muth, and zinc ; but not so readily with copper, arsenic, and 
antimonj'-, and with platina and iron scarcely at all. The 
resulting compounds between mercury and the other metals 
are called amalgams. '- 

Mercury has such an affinity for gold and tin as to dis- 
solve these metals in small pieces, at common temperatures. 
In the mines of South America, a great proportion of the 
gold was formerly procured by amalgamation. Sand, con- 
taining particles of gold, was agitated in a close vessel with 
mercury, and the two metals thus brought in contact, united 
and formed an amalgam. This was then distilled in an iron 
vessel, by which the mercury was driven away, while the 
gold remained. 

At the present time, the gold-beaters make use of the same 
m.eans to obtain the small particles of the metal contained 
in the sweepings of their shops. The sweepings being 
placed in a close vessel, and agitated with mercury, an amal- 
gam is formed. The gold is then separated by pressing the 
amalgam in a buckskin bag, which forces the mercury 
through the pores of the leather, while the gold is retained. 

Mercury is apphed to many other uses in the arts, and is 
a constituent in several important medicines. 

424. Silvering Looking-glasses. — The silvering on the 
backs of looking-glasses is an amalgam of tin, and is put on 

V/hat is the specific gravity of mercury? At what temperature does mer- 
cury boil, and at what temperature does it freeze ? When solid, what pro- 
perty common to many other metals does it possess ? What are the obvious 
indications of impurity in this metal ? What is ethiops mineral ? When 
mercury combines with other metals, what is the compound called ? How is 
gold obtained by mercury ? How do gold-beaters obtain the small particles 
of gold from among the sweepings of their shops ? What is the composition 
called the silvering, on the backs of looking-glasses ? 



232 MERCURY. 

in the following manner : A sheet of tin foil is laid perfectly 
smooth on a slab of marble, and on the tin foil, n:iercurj is 
poured, until it is about the eighth of an inch thick ; the aitrac 
tion of the metals for each other, keeping the mercurj from 
running off. When the mercury is spread equally over the 
surface, the glass plate is run or slid on. I'his is so man- 
aged by partly immersing the end of the plate in the ed^ce 
of the mercury, and pushing it forward, as to entirely exclude 
the air from between the metal and the glass. Weights are 
then laid on the plate to press out the mercury, which does 
not amalgamate with the tin. In about 24 or 36 hours the 
amalgam adheres to the plate in the manner we see it on 
looking-glasses. The glass, therefore, merely serves to keep 
the amalgam in its place, and being transparent, to transmit 
the image which is reflected from the surface of the metal. 
Could the mercury be kept from oxidation, and be retained 
in its place without the glass plate, such mirrors would be 
much more perfect, since the glass prevents some of the rays 
of light from passing to and from the metal. 

MERCURY AND OXYGEN. 

PEROXIDE OF MERCURY, 216. 

1 eq. Mercury, 200 + 2 eq. Oxygen, 16. 

RED PRECIPITATE. 

425, This compound is commonly formed by dissolving 
mercury in nitric acid, and then exposing the nitrate to such 
a degree of heat as to expel all the acid. It is in the form of 
small, shining crystalline scales, of a red color. When 
exposed to a red heat, this oxide is reduced, and converted 
into oxygen, and metallic mercury, a circumstance on which 
its arrangement in the present class depends. When long 
exposed to the action of light, the same effect is produced. 
Red precipitate is employed in medicine chiefly as an escha- 
rotic. 

It will be observed at the head of this section, that the 
peroxide of mercury is composed of 200 parts of the metal, 
combined with 16 parts or two equivalents of oxygen. The 
protoxide of this metal consists of 200 mercury, and 8 oxy- 
gen, these compounds conforming precisely to the doctrine 



Describe the process of silvering a plate of glass. In fonnning a looking- 
glass, what is the use of the glass plate ? What is the conipositi-:)n of perox 
ide of mercury ? By what simple process is it obtained ? How may this 
oxide be decomposed ? What is the use of red precioitafp. 7 



MERCURY. 233 

of definite and multiple proportions, as formerly explained 
The reason why so large a number as 200 is taken for the 
equivalent of mercury, and some other metals, will be under- 
stood when it is recollected that the data from which all the 
proportional numbers are estimated, is the proportions of 
hydrogen and oxygen forming water. The proportion of 
oxygen in this compound being 8, and this number for 
oxygen being fixed, that for mercury is 200, because it 
is found by experiment, that these are the smallest propor 
tions in which these two bodies combine. 

MERCURY AND CHLORINE. 

F ROTOCHLORIDE OF MERCURY, 236. 

1 eq. Mercury, 200+1 eq. Chlorine, 36. 

C A L O M E .L . 

426. When chlorine, a gas formerly described, is brought 
in contact with mercury, at common temperatures, a com- 
bination takes place between them, amounting to one pro- 
portion of each, forming a protochloride of the metal. This, 
however, is not the common method of preparing calomel ; 
the two constituents being more conveniently combined in 
their proper proportions, by mixing the bichloride of this 
metal with an additional quantity of mercury. The bichlo- 
ride of mercury contains, as its name signifies, two propor- 
tions of chlorine and one of the metal. This compound is 
known under the name of corrosive sublimate. It contains 
mercury 200, and chlorine 72 parts by weight. When this 
salt is triturated with mercury, the metal absorbs a part of 
the chlorine, and the whole is converted into a protochloride, 
or calomel. The proportions are 272 parts, or 1 equivalent 
of the corrosive sublimate, and 200 parts, or I equivalent of 
the mercury. This process afibrds a beautiful illustration 
of the truth of the doctrine of definite proportions ; for when 
these equivalents are mixed in a mortar, and then sublimed 
by heat, 86 parts, or 1 proportion of the chlorine is trans- 
ferred from the bichloride to the metaUic mercury, thus con- 



Explain the reason why the combining number for mercury is 200. What 
is said of the combination between mercury and the gas chlorine, at common 
temperatures? What common name has the protochloride of mercury? How 
does the protochloride differ from the bichloride of mercury ? What is the 
common name for the bichloride of mercury? What is the common mode of 
making calomel ? What proportions of corrosive sublimate and mercury 
combine and form calomel ■? 



234 SILVER. 

verting the whole into 472 parts of protochloride of mercury, 
or calomel. 

This process also shows, in a striking manner, the effects 
of different proportions of the same principles, on the quali- 
ties of bodies. Corrosive sublimate is one of the most 
active and virulent of all metalHc poisons, and in doses of 
onij a few grains, occasions the most agonizing symptoms, 
which commonly end in death. But calomel is a mild and 
safe medicine, which may be taken in doses of 60, or even 
100 grains, without injury. And yet the only chemical 
difference between these two substances is, that the calomel 
is a compound of 1 atom of chlorine combined with one 
of mercury, while corrosive sublimate consists of 2 atoms 
of the first and 1 of the metal. 

MERCURY AND SULPHUR. 

SULPHURET OF MERCURY, 216. 

1 eq. Mercury, 200+1 eq. Sulphur, 16. 

CINNABAR. 

427. Cinnabar is prepared by fusing mercury and sul- 
phur together, and afterwards subliming the compound. 
When this compound is reduced to a fine powder, it forms 
the well known pigment vermillion. Cinnabar occurs in 
nature, in large quantities, and is the substance, as already 
stated, from which mercury is chiefly obtained. 

SILVER. 

Equivalent, 110. 

428. Silver is found native in small quantities. It also 
occurs mixed with several other metals, as copper, antimony, 
arsenic, and sometimes with gold, but is chiefly found in 
combination with sulphur, forming a sulphuret of silver. 

This metal, when pure, admits of a lustre only inferior 
to that of polished steel. Its specific gravity is 11 , being 
about half that of platina. In malleability and ductility it 
excels all the other metals except gold and platina. 

Silver is fused by the heat of a common furnace, and by 
a long continued and high degree of heat it may be vola- 

What two principles are strikingly illustrated by this combination ? What 
is the composition of sulphuret of mercury? What is the more common 
name for this compound ? What is vermillion? In what state does silver 
occur? What are the substances with which it is chiefly found combined? 
vVhat is its specific gravity ? What is said of its m.alleability and ductility ' 



SILVER. 235 

tilized, or turned into vapor. Bj^ slow cooling, this -metal 
may be obtained in regular crystals. It is not oxidated by 
exposure to the combined action of heat and moisture, but 
is readily tarnished by sulphureous vapor. Sulphuric acid 
dissolves this metal, when assisted by heat, but its proper 
solvent is nitric acid, with which it readily combines, and 
when the solution is evaporated, forms nitrate of silver, a 
substance known under the name of lunar caustic. 

Silver is precipitated from its solutions, by several of the 
other metals, in its metaUic form. This happens when any 
other metal, having a stronger affinity for oxygen than 
silver, is placed in a solution of this metal. 

If a quantity of nitrate of silver, or lunar caustic, be 
dissolved in water, and a slip of clean pohshed copper be 
dipped into it, the copper v/ill be covered with a coat of 
silver. 

429. Diana's silver tree. — Diana's silver tree is made by 
precipitating silver from its solution, by means of mercury. 
This interesting experiment may be performed in the follow- 
ing manner. Mix together six pa^^.s of a solution of nitrate 
of silver, and four parts of a solution of nitrate of mercury, 
both completely saturated. Add a small quantity of rain 
water, and put the mixture into a glass decanter, containing 
six parts of amalgam, made of seven parts of mercury, by 
weight, and six parts of silver leaf In the course of some 
hours there will appear small shining scales of metallic 
silver on the amalgam, which will increase, and shoot out 
in the form of a silver tree, producing a very beautiful 
appearance. 

430. Silvering powder. — Silvering powder may be pre- 
pared in the following manner. Precipitate silver from its 
solution in nitric acid, by dropping into it some plates of 
clean copper. Take 20 grains of this powder, and mix with 
it two drachms of cream of tartar, the same quantity of 
common salt, and half a drachm of alum. These articles 
must be finely pulverized, and intimately mixed in a mortar. 
If a little of this powder be moistened, and rubbed on a 
clean surface of brass or copper, the silver will be precipi- 
tated, and the surface of the metal will be covered with it. 



How may silver be obtained in crystals? What vapor readily tarnishes 
silver ? What is the proper solvent of this metal ? V/hat is the salt formed 
wheh silver is dissolved in nitric acid ? How is lunar caustic formed ? How 
may silver be precipitated in its metallic form? What is the process foi 
forming Diana's silver tree ? How may silvering powder be prepared ' 



236 «OLD. 

In iliis way the silvering of candlesticks, or other articles, 
where it is worn off, may be replaced. The addition of the 
otiier articles to the precipitated silver, probably serves no 
other purpose than to keep the surface of the brass per- 
fectly clean, and free from oxide, as the powder is rubbed on. 

431. Silvering ivory. — Silver may also be preci])itaied on 
ivory, and then revived by the action of solar light. Into 
a dilute solution of nitrate of silver, immerse a slip of pol- 
ished ivory, and let it remain until it acquires a yellow 
color, then place it in a tumbler of pure water, and expose 
it to the direct rays of the sun for a few hours, or until it 
turns black. If now it be gently rubbed, the surface will 
be changed into a bright metallic one, and the slip of ivory 
will, in appearance, be transmuted into one of silver. This 
change is caused by the deoxidizing power of the solar 
rays, in consequence of which the oxygen is separated 
from the silver, and the metal reduced to its former state. 

432. A very useful solvent of silver is made by dissolving 
one part of nitre with about eight parts of strong sul])huric 
acid. This solvent, whv n heated to about the temperature 
of boiling water, will dissolve silver, without acting on 
gold, copper, lead, or iron, and hence may be conveniently 
used to extract the silver from old plated goods, &c. 

The combining number for silver is 110, it having been 
found that the oxide of this metal contains 110 silver, and 
8 oxygen. 

The sulphuret of silver is composed of 110 of the metal, 
and 16 sulphur. 

GOLD. 

Equivalent, 200. 

433. This well known precious metal is found only in 
the metallic state, either alone, or mixed with other metals ; 
consequently, there is no such thing as an ore of gold. 
Gold is sometimes found disseminated in rocks, but always 
m its metallic state, and never mineralized by sulphur, 
oxygen, or any other substance. Its specific gravity is 19. 
It is the most malleable of all the metals, and in ductilitj' 
is only excelled by platina. 

What is the use of the silvering powder? Of what use are the olhcr in- 
greciients in this powder besides the precipitated silver ? Wliul is the process 
for silvering ivory I How do you account for the return of the silver to its 
metallic state by being placed in the sun? What is the composition of a 
solvent for silver, which does not act upon other metals? What is tX^e 
equivalent number for silver ? In what state is gold always found ? 



GOLD. 237 

434. MaUeability of gold. — The extent to which a given 
portion of this metal may be spread, and still continue a per- 
fectly unbroken surface, is truly astonishing. A single 
grain of the best wrought gold leaf is found to cover fifty- 
six square inches, and it would take nearly 282,000 such 
leaves to make an inch in thickness. This, however, is not 
the utmost limit to which its tenuity may be extended, for 
the wire used by lace makers is drawn from an ingot of 
silver, gilded with this leaf, and from the diameter of the 
ingot, compared with that of the wire, it has been found 
that the covering of gold on the latter is only a twelfth part 
of the thickness of gold leaf Supposing the leaf, when 
first placed on the silver, to have been the 30 thousandth 
part of an inch in thickness, the covering on the wire woidd 
require 360,000 times its own thickness to make an inch; 
and still this covering is so entire that, even with a micro- 
scope, the silver is not to be seen. 

Gold is the only metal which can be made so thin as to 
transmit the rays of light ; and the rays so transmitted, 
instead of being of the same color with the metal, are green. 

This metal, when pure, is not oxidated, or otherwise 
altered, hy being kept in fusion, in the highest heat of a 
furnace for any length of time. Sulphuric, nitric, or muri- 
atic acid, do not, alone, produce the least action on gold ; but 
when two parts of nitric and one of muriatic acid are mixed, 
forming aqna regia^ the mixture dissolves this metal with 
facility. Put some nitric acid into one vessel, and some 
muriatic acid into another, and throw a little gold leaf into 
each. Not the least effect on either will be produced ; but 
if the contents of one vessel be poured into the other, imme- 
diate action will ensue, and the metal will soon be dis- 
solved. 

The solution of gold is decomposed by many substances 
which have a stronger attraction for oxygen than this 
metal has, and by absorbing the oxygen, restores the gold 
to its metallic state. 

435. Hydrogen precipitates gold. — If a piece of ribbon, 
or other substance, be moistened with some dilute solution 



Ar .icre any ores of gold? What is the specific gravity of gold ? What 
illustrations are gi ven of the mallealnlif y of gold ? What is said of the thicK 
ness of this metal on the wire used by lare makers? What is said of 
the light seen through gold leaf? How is gold affected by continued fusion 
at the highest degrees of heat ? What acids dissolve gold ? How may the 
sOiUlions of gold be decomposed ? 



238 PLATINUM. 

of gold, and exposed to the action of a current of hydrogen, 
the gold will be revived, and the ribbon, or other substance 
will be covered with a film of gold. By means of a camel 
hair pencil, the solution may be apphed to the ribbon in 
regular figures, and as the appearance of the ribbon is not 
changed by the application, until the hydrogen is thrown 
upon it, a striking experiment may be made in this way. 
The hydrogen must be applied while the ribbon is moist, 
and may be blown on, through a tube attached to a bladder 
containing it. 

436. Sulphuric ether precipitates gold. — Sulphuric ether 
precipitates gold, but instantly dissolves the precipitate, 
forming an etherial solution of the metal. This solution 
is sometimes employed to gild lancets, scissors, and other 
instruments, in order to preserve them from rust. This is 
readily done by the following method. Into a given quan- 
tity, say an ounce of the nitro-muriatic solution of gold, 
pour twice as much sulphuric ether ; shake the vessel, and 
let it stand two or three minutes, and then pour into another 
vessel about one third of the mixture. The acid does not 
mix with th^e ether, but settles to the bottom of the vessel, 
leaving the ether in possesion of the gold on its surface ; 
the portion decanted into the other vessel, therefore, is an 
etherial solution of gold. Any perfectly clean and polished 
steel instrument will be covered with a coat of gold, if 
dipped for a moment into this solution. When taken from 
the ether, it should be instantly plunged into pure water, to 
wash off any particles of acid which may be retained in 
the solution. The instrument may afterwards be burnished, 
when it will have all the appearance of the best gilding. 

In this case the gold appears to be in its metallic state, 
and to be retained on the surface of the steel by the attrac- 
tion of cohesion, while the ether evaporates. 

PLATINUM. 

Equivalent, 96. 

437. Platinum is a white metal, resembling silver in 
color, but a little darker. It is the heaviest of all known 
bodies, having a specific gravity of 22. 

In what manner may figures of gold be made on ribbon ? What are the 
directions for making an etherial solution of gold? In what manner may 
steel instruments be gilded with an etherial solution of gold? What is the 
color of platinum ? Wliat is its specific gravity ? Is there any known bod> 
of greater specific gravity than platina ? 



PLAl'INUM. 239 

This metal comes chiefly from several parts of South 
America, where it is found in small grains, or scales, exceed- 
ingly heavy, and nearly the color of wrought iron. In this 
state it is ahoyed by several other metals, and requires to 
be purified before it is malleable. It was first discovered 
in 1741, but has not been applied to any considerable use 
until within the last thirty years. This metal has lately 
been discovered in considerable quantities in Russia, and is 
emploj^ed for the purposes of coin, for which it is well 
adapted. 

Platina, like iron, may be welded, and like gold, suffers 
no change from the combined agencies of air and moisture, 
or by long continued heat. For many purposes, therefore, 
it is the most valuable of all the metals. 

This metal is so difficult of fusion, as to undergo the 
greatest heat of a smith's forge without the least change : 
none of the acids act on it, except the nitro-muriatic, the 
solvent of gold. 

438. Platinum is purified and obtained in a malleable 
state by dissolving the grains in 8 times their weight of 
aqua regia, assisted by heat. The acid only dissolves the 
platinum, leaving the iridium and osmium, the metals with 
which it is alloyed, in the form of a precipitate at the bottom 
of the vessel. The acid solution is then evaporated, and 
the metal precipitated by muriate of ammonia. The pre- 
cipitate thus obtained, is heated in a crucible, lined with a 
mixture of clay and charcoal, to the utmost degree that can 
be attained in a blast furnace, when the ammonia and acid 
are driven off, and the fused metal falls to the bottom of the 
crucible. It is afterwards several times heated, and ham- 
mered, when it becomes both ductile and malleable. In 
small quantities, this metal may be fused by the compound 
blowpipe. 

Platinum combines with many of the other metals by 
fusion, and forms alloys which possess various properties, 
some of which are useful. 

Copper, when alloyed with from one-sixth to one twenty- 
fifth part of platina, becomes of a golden color, is much less 
readily oxidated than before, and receives a fine polish. 

In what countries is platina found? When was this metal discovered? 
In what respect does platina possess the property of iron ? In what respect 
is this metal like gold ? What is said of the action of heat, and of the acids 
on platinum ? How is this metal purified and rendered malleable ? Does 
platinum form alloys with the other metals by fusion? 



240 



PLATINUM. 



With iron, platina is said to form a compound highly 
esteemed by the Spaniards, for the purpose of making gun 
barrels, which are stronger, and less apt to rust, than iron 
alone. 

From its infusibilitj, and the difficulty with which it is 
oxidated, this metal is highly useful in the arts, and par- 
ticularly for making various chemical and philosophical 
instruments. 

439. Retorts of platina are now employed instead of lead, 
for the distillation of sulphuric acid. Being acted on neither 
by heat, nor any single acid, such vessels will probably last 
even for centuries without repair. Their expense would, 
however, often be an objection to their use. In Mr. Ten- 
nant's great works for the manufacture of bleaching salt, at 
Glasgow, it is said there are nine platina retorts, which cost 
about 2,500 dollars each. 

440. Aphlogistic lamp. — Platina is the slowest, or most 
imperfect conductor of heat among the metals, and from this 
quality, together with that of sustaining a high degree of 
heat without oxidation, it may be employed to construct the 
aphlogistic or jlameless lamp. 

This curious lamp retains a coil of platina wire constantly 
at a white heat, without either flame or smoke. It may be 
constructed in the following manner : 

The platina wire to be used for this purpose is about the 
thickness of card, or brass wire, No. 26. If larger, the heat 
is carried off too fast, and 
the ignition ceases ; and if 
much finer, it does not re- 
tain sufficient heat to keep 
up the evaporation of the 
alcohol, by the combustion 
of which the heat of the 
wire is maintained. 

Such a piece of wire, six 
or eight inches long, a piece 
of glass tube, and a low 
vial, are the chief mate- 
rials for the construction of 
this lamp. 

The coil A, Fig. 75, is 
made by winding the wire 
round a piece of wood cut 
of the proper size and shape. 



Fi2. 75 




litlBiilliillUIUiUIUlUIUIIIIilUiEiUiniUUUIUBS 



PLATINU.M. 241 

The size is determined hy that of the aperture of the tube, 
allowing for the diameter of the wire. Its shape is a little 
conical, or tapering upwards. In winding the coil, it is 
best that the turns of the wire should come in contact, and 
afterwards be gently extended, so as to come as nearly as 
possible to each other without touching. The diameter of 
the coil may be one-fourth, or one-sixth of an inch, and its 
length half an inch, containing twenty or thirty turns of 
the wire. 

B is a glass tube three or four inches long, containing the 
cotton wick by which the alcohol is carried up to the wire. 
The wick passes about half way through the coil. 

C is the body of the lamp which contains the alcohol. 
It is a low vial, or glass inkstand, capable of holding two 
or three ounces. The glass tube passes through a cork, 
and dips into the fluid. Z) is a small tube through which 
the alcohol is poured. This must be stopped to prevent 
evaporation. 

When the lamp is thus prepared and filled with alcohol, 
the fluid is set on fire by holding the platina wire in the 
flame of a candle, and after a few minutes, or when the coil 
becomes red hot, the flame is blown out, and if every thing is 
properly adjusted, the wire will remain red hot as long as 
the vial contains alcohol. 

441. The following appear to be the causes of the perma- 
nent ignition of the wire. Alcohol, when in the state of 
vapor, combines with oxygen with facility. The tempera- 
ture of the wire is raised by the flame of the candle to about 
1000°, the point at which alcohol combines with oxygen, 
or is combustible. When this is once effected, the caloric 
extricated by the combustion of the alcohol is sufficient to 
keep the coil at a red heat, which again is the temperature 
at which alcohol is combustible, so that one portion of alco- 
hol, by the absorption of oxygen, and the consequent evolu- 
tion of heat, prepares the wire to efTect the combustion of 
another portion, and as the alcohol rises in a constant stream 
of vapor, so the ignition is constant. 

In cases where a fight might be suddenly wanted, this 



What alloys of platina are mentioned as being useful? For what useful 
pui-poses has the pure metal been employed ? Is platina a good or bad con- 
ductor of heat ? What is the aphlogistic or flaraeless lamp ? Explain Fig. 75, 
and describe the construction of the fliimeless lamp. With what fluid is the 
lamp filled? How is it lighted? Explain the principles which cause the 
permanent ignition of the platina wire. 

]] 



242 METALS 

lamp IS highly convenient, for by touching a match to the 
coil, and then to the wick of a candle, a hghti-^^ immediately 
obtained. 

Platinum combines with oxygen m two proportior«^, fonr 
ing the 

Protoxide, 1 eq. plat. 96+1 eq. oxy. 8. 

Peroxide, 1 eq. plat. 96 + 2 eq. oxy. 16. 

PALLADIUM AND RHODIUM. 

442. These two metals were discovered by Dr. Wollastor 
in 1803, in the ore of platinum. When the ore is digested in 
nitro-hydrochloric acid, the platinum, together with palla- 
dium, rhodium, iron, copper, and lead, is dissolved ; while 
a black powder is left, consisting of osmium, and iridium, 
mixed in general with a considerable quantity of titanate of 
iron and silicious minerals. 

PALLADIUM. 

Equivalent, 54. 

443. This is one of the rare metals, and is obtained in its 
pure state with difficulty. It resembles platina in color and 
lustre. It is malleable and ductile, and is much "harder than 
platinum. Its specific gravity is about 11.8. Its fusibility 
is intermediate between gold and platinum, and when in- 
tensely heated by the oxy -hydrogen blowpipe, is dissipated 
in sparks. It is oxidized and dissolved by nitric acid, but 
its proper solvent is nitro-hj^drochloric acid. Its protoxide 
forais beautiful red salts, from which metahic palladium is 
precipitated by the sulphate of proxide of iron. Its com- 
pounds are not numerous, though it combines with oxygen 
in two proportions, fonuing a protoxide and a binoxide, with 
chlorine, forming the protocJdoride and the bichloride, and 
with sulphur, forming the protosulpJiuret. 

RHODIUM. 

Equivalent, 45. 

444. On immersing a plate of clean iron into the solution 
from which palladium and most of the platinum have been 

Wliat is the use of the aphlogistic lamp? AVhat is the equivalent luunhei 
for platinum ? What are the names of the oxides of this metal, and what the 
proportions of their elements ? Where were the metals palladium, rhodium, 
iridium, and osmium, first discovered ? What is the color, and what are the 
properties of palladium ? What is the corabming number for palladium ? 
What is the specific gravity of rhodium ? What is the color, and what are 
the properties of rhodium ? 



METALS. 243 

precipitated, the rhodium, with small quantities of lead, cop- 
[^x, and platinum, is thrown down in the metalhc state. The 
rhodium is afterwards separated hy means of several pro- 
cesses not necessary to detail. It is procured in form of a 
black powder, which being fused by the strongest heat of a 
wind furnace, produces the metal in question. Its color is 
white, with a metallic lustre, and a specific gravity of about 
11. It is extremely hard, scratching hardened steel, and is 
not attacked by any of the acids in its pure state. Chemists 
are acquainted with two oxides of rhodium, and several salts, 
which are either red or yellow. It is only soluble in acids 
when alloj^ed with other metals. 

Use. — It is emploj^ed for the points of metallic pens, for 
which, owing to its extreme hardness and insolubility in 
acids, it is admirably adapted. The gold pens of the pre- 
sent day owe their lasting property to this metal. 

OSMIUM AND IRIDIUM. 

445. These metals owe their discovery to Mr. Tennant, 
in 1803. The black powder, mentioned at the beginning of 
this article, as containing these metals, is the source whence 
they were obtained. The manipulations resulting in ob- 
taining them in the pure state, are long and difficult. 



Equivalent, 100. 

446. This metal appears at first in the form of a porous 
mass, which acquires metallic lustre by friction. It takes 
fire when heated in the open air, and is readily dissolved by 
nitric acid. In its densest state its specific gravity is 10. 
It combines with oxygen and the acids, forming many com- 
pounds, which our limits do not allow us to describe. 

Osmic acid. — This is the product of the oxidation of os- 
mium by acids, or by combustion. It is in the form of elon- 
gated, transparent crystals, having an exceedingly acrid 
vapor, exciting cough, producing tears, and a copious flow 
of saliva. Its odor is disagreeable and pungent, somewhat 
like that of chlorine, and this property suggested its name 



From what circumstance is the name of this metal derived? What is the 
equivalent number of rhodium? How are iridium and osmium obtained' 
What is the specific gravity of iridium ? What is said of its fusibility, and 
solution in acids ? What are the properties of osmium 1 How is osmium 
obtained in its pure state ? 



244 MKTALS. 

from a Greek word signifying odor. Neither the metal, nor 
us compounds, have been appHed to any use. 

IRIDIUM. 

Equivalent, 96. 

447. This is a very brittle metal, and, without care, will 
fall into powder in attempting to burnish it. When polished, 
it resembles platinum in color and lustre. Of all known 
metals it is the most infusible. Berzelius never succeeded 
in melting it, but Mr. Children, with his immense galvanic 
battery, fused it into a brilliant metallic globule of a white 
color, having a specific gravity of nearly 19, being, in respect 
to this property, next to platinum. 

Iridium combines with oxj^gen and chloric acid, forming 
oxides and chlorides. 

CLASS II. 

448. Metals, the oxides of which are not reducible to the 
metallic state by heat alone. 

Order 1. — Metals which decompose loater at common tem- 
peratures. These are 

Potassium, Lithium, Strontium, 

Sodium, Barium, Calcium. 

449. These metals attract oxygen with the most intense 
degree of force. They absorb it from the atmosphere, and 
even decompose water, by combining with its oxygen, at 
common temperatures. Such is the force by which they 
hold this principle, that their oxides had resisted all attempts 
to decompose them, until the discovery of galvanism placed 
in the hands of men a more powerful decomposing agent 
than was before known. By means of the most intense 
electrical repulsion, the alkahes, before considered as simple 
bodies, were shown to be the oxides of metals. After the 
secret of their composition was known, chemists devised 
other and less expensive means of effecting their decompo- 
sitions, so that at the present time, sodium and potassium, 
at first the most expensive of all substances, are within the 
means of any one. 



What is the definition of class II? What is the definition of order 1st, of 
this class ? What are the names of the metals belonging to this order ? What 
is said of the intense degree offeree with which these metals attract oxygen? 
By what deeomposing agent were the alkalies shown to be the oxides of 
metals ? 



POTASSIUM. 



245 



POTASSIUM 

Equivalent, 40. 

450. Decomposition of Potash. — If a small piece of pure 
potash, slightly moistened, be put between two plates of pla- 
tinum connected with the poles of a galvanic battery of 200 
double plates, the alkali will soon be fused and decomposed. 
Oxygen will separate at the positive pole, and small metallic 
globules, like quicksilver, will appear at the negative pole. 
In this manner. Sir H. Davy first determined the composi- 
tion of potash, and separated its elements. Potash, there- 
fore, is a compound consisting of a metal called potassium^ 
united to oxygen. 

By this process the metal can be obtained only in minute 
quantities; but chemists, now understanding that to obtain 
potassium in any quantity, only required that the oxygen 
should be separated from the potash, soon found more ready 
means of performing the experiment. The following is the 
method first employed by Thenard : 

451. Thenard' s process. — A clean and perfectly sound 
gun-barrel is provided, and bent in the manner shown in 




What is the process by which Sir H. Davy decomposed potash^ 



246 METALS 

Fig. 76, and covered with an infusible lute between the let- 
ters O and E, Fig. 1. The interior of the luted part is filled 
with clean iron turnings, and pieces of fused potash are 
placed loosely in the part between E and C. 

A, A, is a copper tube and small receiver, adapted to the 
extremity of the barrel O, and to each other, by grinding. 
This apparatus is then transferred to a furnace, arranged aa 
shown by Fig. 2. At each end of the ban*el are the glass 
tubes X and T, dipped into cups of mercury, so as to let the 
air from the barrel escape as it is rarefied by the heat, and 
at the same time prevent its return. The furnace is supplied 
with air by a double bellows entering at B, and a small wire 
basket, G, is suspended in the space between E and C. The 
part of the barrel in the furnace is now raised to a white 
heat, and the escape of air by the tube X, shows that all 
is tight. Some burning charcoal is now placed in the end 
E, of the basket, which causes a portion of the potash to 
liquefy and fall into the lower part of the gun-barrel, among 
the iron turnings. Hydrogen gas instantly escapes at the 
tube X, in consequence of the decomposition of the water 
contained in the potash, by the heated iron. The copper 
tubes, A, A, must now be kept cool by wet cloths. When 
the evolution of gas ceases, fresh charcoal is placed 
under the potash, and so on till the whole has passed down. 
If too much potash be allowed to fall down at once, the 
extrication of hydrogen at X, will be violent, and should 
be avoided. If the space between A, and O, should become 
stopped by potassium, the gas will issue at the tube T, and 
then some burning charcoal must be placed between A and 
O, which will remove the obstruction. 

When all the potash has been fused and made to pass 
among the iron turnings, the process is finished, and then 
the tubes X and T, must be removed, and the ends of the 
barrel instantly stopped with corks until the apparatus has 
cooled. The barrel is then carefully removed, and a little 
naphtha suffered to run through it, by which the potassium 
is coated and thus preserved from the contact of air, while 
pouring out of the barrel. The potassium is found in glo- 
bules in the tube and receiver, A, A. 

452. The success of this process is certain, if the heat is 



Describe Fig. 75, and exulain the method of decomposing potash by means 
of iron turnings and heat. What is the condition on which it is said this 
experiment will certainly succeed ? 



POTASSIUM AND OXi ^XN. 247 

sufficient; but the barrel, if not caret ully cov^isd Wiih lute, 
is apt to melt, when most, if not all, the potassium will be 
lost. 

In this process, the decomposition of the potash is effected 
by the iron turnings, which at a high heat have so strong 
an attraction for oxygen, as to absorb it from the potassium, 
and as the iron combines with the oxygen, the ;^otassium is 
left in its pure state. 

Potassium is solid at ordinary temperatures, but becomes 
fluid at 150'^, and then appears like mercury. It is per- 
fectly opaque, and a good conductor of electricity and caloric. 
At the temperature of 50°, it is soft Hke wax, and yields to 
the pressure of the fingers. In this state it resembles an 
amalgam of mercury and tin. Its specific gravity is 0.865, 
water being 1.000. 

The most prominent chemical pr(?perty of this metal is its 
extreme a\ddity for oxygen. When exposed to the air, it 
oxidizes rapidly, and when thrown on water it decomposes 
that fluid, by absorbing its oxygen with such rapidity as to 
set itself on fire, and burns with a white flame, and great 
evolution of heat, while swimming on its surface. 

POTASSIUJI AND OXYGEN. 

PROTOXIDE OF POTASSIUM, 48. 

1 eq. Potassium, 40+1 eq. Oxygen, 8. 

POTASH. 

453. Potassium combines w^ith oxygen in two proportions, 
forming the protoxide, and peroxide of potassium. The first, 
which is common potash, is formed whenever potassium is 
put into water, or exposed to dry air, or oxygen gas. 

The proportion of oxygen which this metal absorbs, to 
convert it into potash, is readily ascertained by the volume 
of hydrogen hberated when it acts on water. For, when 
potassium is plunged at once under that fluid, it is oxidized 
without the evolution of light or heat, and it is found that 

What is the principle on which the decomposition of the potash is effected 
by means of iron turnings and heat ? What is the appearance of potas- 
sium? Is it a conductor of caloric and electricity? At what temperature 
does it become fluid, and at what temperature is it solid? What is the spe- 
cific gravity of this metal ? What phenomena are produced when potassium 
is thrown on water? In how many proportions'does potassium combine with 
oxygen? What common substance is formed when potassium is exposed to 
the air? When potassium is plunged under water, how is it ascertained what 
quantity of oxygen it absorbs ? 



248 POTASSIUM AND OXYGEN. 

each grain of the metal so placed, separates 106 cubic inches 
of hydrogen gas. Now, by knowing previously what are 
the relative volumes and weight of hydrogen and oxygen 
composing water, it is easy to calculate the exact quantity 
of oxygen absorbed by the above data. 

Thus, Sir H. Davy found that 40 grains of this metal 
decompos.^s precisely 90 grains of water. Now, as 9 grains 
of water is composed of 1 grain of hydrogen, and 8 oxygen, 
so 40 parts of potassium combines with 8 parts of oxygen, 
to form oxide of potassium, or potash. Potash is therefore 
composed of 

Potassium, 1 eq. 40 + Oxygen, 1 eq. 8 = 48. 

48 combining number for potash. 

When potassium is allowed to absorb oxygen in the open 
air, or when plunged under water, it combines with only one 
proportion of oxygen, as above stated. But when this metal 
burns in the open air, or in oxygen gas, it is converted into 
an orange colored substance, which is the peroxide of potas- 
sium. This is composed of 

Potassium, 1 eq. 40+4 eq. Oxygen, 24=64. 

454. The potash of commerce is obtained from the Ij^e 
of wood ashes, boiled down in pots, and hence the name 
potash. It is chiefly used in the manufacture of soap and 
glass. For the former purpose, the lye itself is often em- 
ployed, and is better than the solid potash, dissolved in 
water, since the potash soon absorbs carbonic acid, and 
then its quality for soap making is in a great measure des- 
troyed. From this circumstance it is, that soap makers 
mix with their lye a quantity of newly burned quicklime, 
which renders the solution of potash caustic, by absorbing 
from it the carbonic acid, with which it has combined. 

Soft soap only can be made from potash, while hard 
soap is made from soda. 

Common green glass is made by fusing sand and wood 
ashes together, by means of an intense heat, produced by 

Suppose 40 grains of potassium decompose 9 grains of water, how does it 
appear in what proportion potassium and oxygen combine ? "VVTiat is the equiv- 
alent number for potash? When potassium is burned in the open air, or in 
oxygen gas, what proportion of oxygen does it absorb ? What is the oxide 
called which is so formed? How is the potash of commerce procured? In 
what manufactures is the article chiefly employed? What is the use of 
quicklime in soap making? How do the soaps made from potash and soda 
differ ? What are the materials for making green glass ^ 



SODA 249 

the combustion of dried wood, in a blast furnace. Flint 
glass, which is perfectly white and transparent, is made by 
fusing together a quantity of potash and white sand, oi 
ground quartz, to which are added a proportion of lead, 
and a little manganese. 

Salt of tartar^ salt of wormwood^ pearl-ash^ and carbonate 
of potash^ are only different names for the same article, 
some of \v*hich are more pure than others. 



Equivalent, 24. 

455. By the same process which showed potash to be a 
compound body, soda was also found to be of the same 
nature. Although first procured by means of galvanism, 
it may be obtained by precisely the same method as that 
described for the production of potassium, only placing 
soda in the gun barrel, instead of potash. 

Sodium has a strong metallic lustre, similar to that of 
silver. It is a little less fusible than potassium, not be- 
coming perfectly fluid until it has acquired the temperature 
of nearly 200°. Its specific gravity is somewhat greater 
than that of potassium, being 0.972. When thrown on 
water it produces a violent effervescence, but does not in- 
flame like potassium. The water is decomposed by its 
action, hydrogen escapes, and there remains a solution of 
soda in the water. Like potassium, it must be preserved in 
a vial, covered by naphtha, — a substance which contains no 
oxygen. 

SODIUM AND OXYGEN. 

PROTOXIDE OF SODIUM, 32. 

1 eq. Soda, 24+1 eq. Oxygen, 8. 

SODA 

456. When the metallic base of soda is burned m dry 
atmospheric air, protoxide of sodium, or soda, is formed. 
The same compound is formed when sodium is thrown into 
water, and the composition may therefore be determined in 

What are the materials for making flint glass ? What other names are 
applied to potash ? What is the process of decomposing soda, and obtaining 
the metal sodium ? What is the appearance of sodium ? In what respects 
does this metal diflfpr from potassium? What is the effect when sodium is 
thrown upon water? How is the metal preserved? What compound is 
formed when sodium is burned in atmospheric air, or thrown into water? 
What is the composition of protoxide of sodium, or soda ? 
11* 



250 SUDIL'M A>.U CHLORINE. 

the manner already described for potassium. From such 
an experiment it has been found that soda is composed of 

Sodium, 1 equivalent, 24 

Oxygen, 1 do. 8 

32, equivalent of soda. 

The peroxide of soda is composed of the same equiva- 
lent of sodium, with two equivalents of oxygen. Sodium 
24, oxygen 16 — 40. 

Soda is readily distinguished from other alkahes by the 
following characters. With muriatic acid it forms the 
common table salt, with the taste of which every one is 
famihar. With sulphuric acid it forms Glauber's salt, or 
sulphate of soda. All the salts of soda are soluble in 
water, and are not precipitated by any other substances. 

SODIUM AND CHLORINE. 
CHLORIDE OF SODIUM, 60. 

1 eq. Sodium, 24+1 eq. Chlorine, 36. 

COMMON SALT. 

457. When sodium is exposed to chlorine, or is heated in 
muriatic acid gas, the salt is formed, well known under the 
name of muriate of soda, or common salt. This is an abun- 
dant product of nature, and exists ready fonned in Spain, 
England, Poland, and other countries, in large quantities. 
In these countries it is dug out of the earth, and is known 
by the name of rock salt. Sea water and certain springs 
also contain this salt in solution. 

When common salt is dissolved in water, and the solu- 
tion is evaporated rapidly, it crj^stalizes in the form of hollow 
four-sided pyramids ; but if allowed to evaporate sponta- 
neously, it occurs in regular cubes. Thus, the crystals 
show in what manner the salt has been manufactured. In 
England, vast quantities of salt are annually raised from 
the mines, chiefly of Cheshire, and purified for sale. The 
impurities consist chiefly of clay and oxide of iron, besides 
which, it contains various proportions of sulphate of mag- 
nesia, or Epsom salt, sulphate of lime, and muriate of lime. 

What is the equivalent number for soda? How is soda distinguished from 
the other alkalies ? What is chloride of sodium ? What the sources of com- 
mon salt ? When a solution of common salt is evaporated rapidly, what is 
the form of its cr>'Stals '' When evaporated slowly, in what form are the 
crystals ? Where are the salt mines of England? "What impurities exist in 
.he Cheshire rock salt ^ 



SODIUM AISJD CHLORINE. 251 

It is purified bj being- dissolved in sea-water, and subse- 
quently evaporated. Formerh^, all the English salt was 
evaporated by artificial heat, the brine being boiled until it 
was ready to shoot into crystals. Its crystals were, there- 
fore, always in the form of hollow pyramids. But it has 
been supposed, by victualers and others, that this salt is far 
less efficacious, as a preserver of animal food, than that 
prepared by the spontaneous evaporation of sea-water in 
hot climates. Hence, salt from the West Indies, which is 
crystalized in solid cubes, has been preferred for curing pro- 
visions for long voyages, or for summer use. In this country, 
although immense quantities of common salt are manufac- 
tured, by the evaporation of water from salt springs and 
from the '• ea, and a sufficient supply for our consumption 
might bf made, yet we annually import large quantities 
from the West Indies, there having been, until lately, an 
opinion that no other kind of salt would preserve animal 
substances through the hot season. 

458. Dr. Henry, for the purpose of ascertaining the differ- 
ence between English salt, crystalized by heat, and that 
from the West Indies, crystahzed by spontaneous evapora- 
tion, analyzed many specimens of each. The result showed 
the presence of sulphate of magnesia and sulphate of lime 
in both, but the difference in the quantity of muriate of soda, 
in several specimens of each kind, was so trifling, as to 
make no possible difference in respect to their preserving 
qualities. It is presumed, therefore, that the prejudices in 
favor of foreign salt ought to be discarded as imaginary, 
and that equal weights of fine or coarse salt, whether made 
by artificial or spontaneous evaporation, are equally effica- 
cious for all purposes. 

Common salt contains no water of crystalization, but 
decripitates remarkably when heated, owing to the conver- 
sion of the water into steam, which is mechanically con- 
fined within its crystals. Its solubility is not, like most 
other salts, increased by heat, and it requires two and a 
half times its weight of water for solution, whether hot or 
cold. 

ITow is this salt purified ? Why were the crystals of this salt always in 
the form of hollow pyramids ? What salt was formerly supposed best for 
the preservation of animal substances ? What is said of the real difference 
between salt made by rapid or slow evaporation ? Does common salt con- 
tain any water of crystalization? Why does common salt decripitate, or 
fly in pieces, when thrown upon a fire ? Is the solubility of this salt 'n 
creased by heat? What quantity of water does it require for solution? 



252 j.fTHlUM. 



i. I T H I U M , 



Equivalent, 10. 

359, Lithia is an alkaline substance, discovered by M. 
Arfwedson, a Swedish chemist, in 1818. It exists in the 
minerals called spodumene^ and lepidolite^ and also in some 
varieties of mica. 

This alkali is distinguished from potash and soda, by its 
power of neutralizing larger quantities of the different acids, 
and by its action on platinum, when melted on that metal. 

In respect to its metallic base, called lithium. Sir H. Davy 
succeeded, by means of galvanism, in obtaining a white 
metal from lithia, similar in appearance to sodium, but it was 
oxidized so rapidly, and reconverted into the alkali, that 
it could not be collected. 

Fom the experiments of several chemists on the sulphate 
of lithia, it is inferred that the alkali, lithia, is composed of 
the metal lithium 10, combined with oxygen 8, making the 
combining number for lithia 18. 

Lithia has been procured only in very small quantities, 
and has never been applied to any useful purpose. 

BARIUM. 

Equivalent 69. 

460. There is a substance called sulphate of harytes^ 
which is found abundantly in nature. By the decomposi- 
tion of this substance, an alkahne earth is obtained, called 
baryta^ or harytes. When barytes, in the form of paste 
mixed with water, is exposed, in contact with mercury, to 
the action of a powerful galvanic battery, its decomposition 
is effected, and the metal barium^ its base, amalgamates with 
the mercury. The amalgam being exposed to heat, the mer- 
cury is driven off, and pure barium remains. 

The metal thus obtained, is of a dark gray color, with a 
lustre inferior to cast iron. It fuses at a heat below redness, 
and at a red heat is converted into vapor, which acts violently 
upon glass. The specific gravity of barium is four or five 
times that of water. When exposed to the air it falls into 

What IS lithia? In what minerals is this alkali found? How is lithia dis- 
tinguished from potash and soda ? What is known concerning the metallic 
base of this alkali ? What are the equivalent numbers of lithium and lithia? 
How is baryta obtained ? By what process is barium separated from baryta? 
What is the color of barium ? At what temperature is barium fusible ? 
Wliat is the specific gravity of barium ? 



METALS 253 

a while powder, ^^ nich is found to be an oxide of barium, or 
barytes. When heated in oxygen, it burns with a deep red 
Hght, and wdien thrown into water, the fluid is decomposed, 
hydrogen being extricated. 

BARIUM AND OXYGEN. 

PROTOXIDE OF BARIUM, 77. 

1 eq. Barium, 69+1 eq. Oxygen, 8. 

BARYTES. 

461. When the metal barium is exposed to the air it falls 
into a powder, which was formerly called pure barytes, or 
baryta, but which Sir H. Davy has proved by the above 
stated experiment, to consist of a metal and oxygen. This 
substance is, therefore, called oxide of barium. 

Oxide of barium may also be obtained by a diiferent pro- 
cess from that above described, viz., by exposing the carbon- 
ate of baryta to an intense heat, mixed with charcoal. 

The carbonate of barytes is found native in small quanti- 
ties, but may be obtained from the sulphate of barytes by a 
simple process. Mix sulphate of barytes in fine powder, 
with three times its weight of carbonate of potash, (pearl- 
ash.) and a proper quantity of water. Let the mixture boil 
for an hour, now and then breaking the lumps into which it 
is apt to run, with a pestle. By this means the two salts 
will decompose each other, and there will be formed carbo- 
nate of barytes, and sulphate of potash. The carbonate may 
now be exposed to a high heat, or it may be dissolved in 
nitric acid, and thus decomposed, which is effected by a 
moderate heat, when protoxide of barium, or barytes, will 
be obtained. This substance is of a white color, has a sharp 
caustic taste ; changes vegetable blue colors to green ; neu- 
tralizes acids, with which it forms salts, and is a strong 
poison. When water is thrown on it, it falls into fine pow 
der, like quicklime, but with a greater evolution of heat. 

Barytes is composed of 

1 equivalent of barium, 69 

1 do. of oxygen, 8 

The equivalent combining number for barytes, 77 

When barium is exposed to the air, what compound is formed? When 
thrown into water, what effects are produced? By what process may barium 
be obtained without the agency of galvanism? How may carbonate of bary- 
tes be extracted from the sulphate ? WTiat are the properties of barytes, or 
protoxide of barium ? What is the composition of barj'tes ? 



254 METALS. 

Barjtes is soluble in about twenty parts of water, at com- 
mon temperatures, and this solution forms a delicate test for 
the presence of carbonic acid. The carbonate of barjtes 
being insoluble in water, a white cloud is instantly formed 
by the union. 

STRONTIUM. 

Equivalent, 44. 

462. The sulphate and carbonate of strontian, or strontia, 
are native salts. They consist of pure strontian, combined 
with sulphuric and carbonic acids. From the sulphate, the 
carbonate may be procured by precisely the same means as 
already described for barytes, and the pure oxide may also 
be obtained, and the metal strontium separated from it, by 
the same process as that described for barytes. 

Strontia resembles baryta in most respects. It slakes in 
water, causing an intense heat, and possesses distinct alka- 
line properties. 

The metal strontium is similar to barium in appearance, 
and when exposed to the air quickly attracts oxygen, and 
is converted into strontia. Perhaps the principal difference 
between these two substances, which has been detected, is 
their different combining proportions with oxygen, and the 
inertness of the oxide of strontium on animals. 

The protoxide of strontium consists of 

Strontium, 1 equivalent, 44 
Oxygen, 1 do. 8 



52 
The oxides of barium, as already stated, are strong poi- 
sons, but those of strontium are inert. 

CALCIUM. 

Equivalent, 20. 

463. When carbonate of lime, or white marble, is ex- 
posed to a red heat, the carbonic acid is expelled, and there 
remains a white caustic substance, well known under the 

In what quantity of water is barytes soluble ? Why is baiytes a test for 
carbonic acid ? How is the carbonate of strontian produced from the sul- 
phate ? How IS the pure earth strontia obtained from the carbonate ? By 
what process is the metal strontium separated from strontia? What is the 
appearance of this metal ? What is the composition of strontia, or the pro- 
toxide of strontium ? What is the combining number of strontia ? What is 
the difference between strontia and baryta ? What is quicklime ? 



.jiM 



METALS. 255 

name of quickli?ne. When this substance is exposed to the 
action of galvanism, in the same manner as akeady de- 
scribed for the decomposition of barjtes, calcium^ the me- 
talhc base of Ume, is separated. This metal is of a whiter 
color than barium, and has a lustre like silver. When ex- 
posed to the air, it absorbs oxygen, and is converted into 
quicklime ; and when thrown into water, the fluid is de- 
composed, its oxygen being absorbed, while hydrogen is 
given off, and a solution of lime remains. 

CALCIUM AND OXYGEN. 

OXIDE OF CALCIUM, 28. 

1 eq. Calcium, 20-4-1 eq. Oxygen, 8. 

QUICKLIME. 

464. From the quantity of hydrogen evolved by the ac- 
tion of calcium on water, it has been determined that lime 
is composed of 

Calcium, 1 equivalent, 20 

Oxygen, 1 do. 8 



Making the equivalent for lime, 28 

Carbonate of lime exists in great abundance as a natural 
product, under the names of limestone, marble^ and chalk. 
Cluickhme, the pure earth, is obtained by exposing the car- 
bonate to heat, and is a substance of great importance in 
the arts, and particularly in building. Mortar is composed 
of this substance, combined with water, and mixed with a 
proportion of sand. 

Q^uicklime absorbs water with remarkable avidity, and 
at the same time a high degree of heat is produced. This 
process is called slaking., and the heat is caused by the con- 
densation of the water into a soHd state, in consequence of 
which caloric is evolved. The hme will remain perfectly 
dry after having absorbed one third of its weight of water, 
which therefore forms a part of the slaked hme, or hydrate 
of lime. 



How may quicklime be decomposed, and calcium, its metallic base, be 
separated? What is the appearance of calcium? How is calcium converted 
into quicklime? What effect is produced when calcium is thrown into 
water? How is the combining proportion of oxygen with calcium deter 
mined? What is the composition of lime, or oxide of calcium? What is 
the equivalent number for lime? What causes the heat, when water is 
thrown on quicklime? What is the scientific name for slaked quicHime'' 



256 METALS 

Hydrate of lime is composed of 

28 parts, or 1 proportion of lime, 
9 parts, or 1 do. of water, 

37 is therefore its combining number. 

465. Lime is very sparingly soluble in water, and it is a 
singular fact, that it is more soluble in cold, than in hot 
water. Thus, Mr. Dalton found that one grain of lime, at 
the temperature of 212° required 1270 grains of water for 
its solution, while at the temperature of 60°, the same 
quantity was dissolved in 778 grains of water. By other 
experiments, it has been found that water, at the freezing 
point, will take up just twice the quantity of lime that it 
will at the boiling point. Consequently, on heating lime 
water, which has been prepared in the cold, a deposition of 
the lime will ensue. Lime water, therefore, when used for 
medicinal purposes, should be prepared in cold, instead of 
hot water, as commonly directed, and should also be kept 
in a cool place. It should likewise be closely stopped from 
the air, for, as the Hme has a strong attraction for carbonic 
acid, of which the atmosphere always contains a small 
portion, if left open, it is soon converted into carbonate of 
lime, as shown by the production of a thin pelhcle on its 
surface. 

Lime water is a delicate test for the presence of carbonic 
acid, with which it forms a white insoluble compound, the 
carbonate of lime. The air from the lungs contains a small 
quantity of carbonic acid, and hence, on blowing into a ves- 
sel of clear lime water, it instantly becomes cloudy, or turbid. 

LIME AND CHLORINE. 

CHLORIDE OF LIME, 92. 

2 eq. Lime, 56+1 eq. Chlorine, 36. 

BLEACHING POWDER. 

466. The gas called chlorine, as already shown, posses- 
ses strong bleaching or whitening powers ; but as it would 

What is the composition of hydrate of lime ? What singular fact is men 
tioned concerning the solubility of lime in cold, and hot water ? How much 
more lime will water dissolve at the freezing than at the boiling point? Had 
lime water, for medicinal purposes, ought to be made with hot or cold water ? 
Why ? Wliy should lime water be closely stopped from the air? Why does 
lime water become cloudy when air from the lungs is blown into it? What 
is the chemical name for bleaching powder? Does the bleaching property 
exist in the lime or in the chlorine^ 



CHLORIDE OF LIME. 257 

be inconvenient to manufacture this gas at every place where 
it is wanted, and as its appHcation is more convenient when 
combined ^vith some other substance, it is found that in prac 
lice, these purposes are best answered by first combining it 
with hme. The manufacture of bleaching powder is a busi- 
ness of great importance, and is carried on in large estab- 
lishments prepared for the purpose. 

467. Retorts for Chlorine. — The retorts, in which the gas 
is extricated, are made of lead or platina. If of lead, they 
must be of new metal and cast, for the gas acts on tin, a 
part of the composition of solder, and since old lead gener- 
ally contains a portion of this metal, owing to its having 
been soldered, it is soon destroyed. These retorts are placed 
in iron vessels of water, to which the heat is applied. In 
large manufactories, each retort is capable of containing 10 
cwt of common salt, ground with from 10 to 14 cwt. of 
black oxide of manganese, in proportion as the latter con- 
tains more or less oxygen. This being introduced, there is 
added from 16 to 18 cwt. of sulphuric acid, of the specific 
gra\dty of 1650. The lime, recently slaked, is contained in 
trays or shallow boxes of wood, placed in a large chamber, 
built of granite, or sihceous sandstone, or lined on the inside 
with lead. This chamber has two windows of glass, oppo- 
site to each other, through which the workmen are enabled 
to see how the process goes on. Every part of this cham- 
ber is made air tight, the door being secured by fat lute, 
and strips of cloth. 

In order to get rid of the remaining gas, after the absorp- 
tion of the lime is completed, there are three trap doors, one 
in the roof, and two in the floor or sides of the chamber. 
These are opened by means of ropes and pullies, so that the 
workmen may avoid the vapor that passes out. 

468. Process for Chlorine. — The lime being placed in the 
boxes, the gas is let into the chamber from the retorts, under 
which a fire is afterwards kindled, in order to hasten the 
process, and obtain more chlorine. The gas, being heavier 
than air, is let in at the upper part of the room, and gradu- 
ally descends, while the air in part mixes with it, and in 
part rises above it. 

What are the advantages of combining the chlorine with the lime for this 
purpose ? Why must new lead be used for retorts in making chlorine 
Describe the chamber in which the lime, for making the chloride of lime, iai 
placed. Wliat contains the lime when placed in the chamber? Into whfltt 
part of the room is the chlorine admitted ? 



258 CHLORIDE Of LIME. 

The lime absorbs the chlorine with great avidity, its con- 
deiisation causing the evokition of a large quantity of calo- 
ric ; the latter circumstance is, however, to be avoided, as 
too high a heat partly decomposes the chloride of lime, by 
expelling the oxygen, and thus forming a chloride of calcium, 
instead of a chloride of lime. The gas is, therefore, admit- 
ted slowly, in order to avoid this consequence. 

The process continues four days, before the absorption is 
considered sufficient to make the best bleaching powder, for 
its quality depends entirely on the quantity of chlorine which 
the lime contains. 

469. In some manufactories, the lime is stirred by means 
of rakes, with long handles, passing through the sides of the 
room, the passages being made close by means of milk of 
lime, or lime moistened, so as to be about the consistence of 
cream, and contained in boxes through which the handle 
passes. In others, the traps above described, are opened at 
the end of two days from the beginning of the process, 
and when the gas has subsided, the workmen enter and 
rake over the lime, so as to present a new surface to the 
action of the gas. The doors and traps are then closed, and 
the gas admitted for two days more, at the end of which 
time the process is finished, and the doors are again opened, 
and the chloride of lime removed, and put into close casks 
for use. 

In general, according to Mr. Gray, a ton and a half of 
good bleaching powder is considered the average product 
of each ton of the salt employed. 

470. It is said that the principal difficulty in the manufac- 
ture of this article, is the production of chloride of calcium, 
by decomposition, instead of the chloride of lime. To under- 
stand the cause of this difficulty, it must be remembered, 
that calcium and chlorine have a stronger affinity for each 
other than calcium and oxygen. Lime is composed of 
calcium and oxygen ; and chloride of lime is therefore 
composed of oxygen, calcium, and chlorine. Now these 
three elements being present, there is formed a chloride of 

Why must the chlorine be admitted slowly ? If the heat rises too high, 
why is there a muriate, instead of a chloride of lime formed ? How long a 
time IS required for making the best bleaching powder ? In what manner is 
the lime stirred, in order to hasten its absorption of the chlorine ? What 
proportion does the bleaching powder formed, bear to the quantity of salt 
employed ? What is said to be the principal difHculty in the manufacture of 
bleaching powder? What is the difference in composition between muriate 
of lime and chloride of lime ? 



CHLORIDE OF LlMi:. 250 

calcium, in consequence of the cause just stated; and in 
proportion as this is formed, the bleaching property of tho 
salt is destroj^ed, this property being possessed only by the 
chloride of lime. The same effect is produced when the 
temperature is raised too high during the manufacture of 
this compound, for then the oxygen of the lime or base is 
expelled, and the calcium and chlorine form chloride of 
calcium. The only mode of avoiding this difficulty appears 
to consist in admitting the chlorine slowly, as already 
stated. 

471. This salt is also subject to decomposition from other 
causes. When mixed with water, and exposed to the 
action of the atmosphere, carbonic acid unites with the lime, 
while the chlorine is expelled, and thus a carbonate instead 
of a chloride remains, or by decomposition of the water, a 
muriate of lime is formed, which is also without bleaching 
properties. 

472. As the goodness of bleaching powder depends en- 
tirely on the quantity of chlorine it contains, it is a matter 
of great consequence to the purchaser to ascertain its 
quality in this respect, by actual experiment. According 
to the experiments of Dr. Ure, hme, under a slight pres- 
sure, is capable of condensing nearly its own weight of 
chlorine ; but according to the same author, the bleaching 
powder of commerce always contains a considerable pro- 
portion of the nitrate of lime, while the chloride itself often 
does not contain more than one half or one third the quan- 
tity of chlorine which the lime is capable of absorbing. 
Hence the consumers of this article are often cheated out 
of one half or two thirds of the price they pay for it, besides 
the delay and vexation incident upcn the failure of the 
process in which it is used. The mr.nufacturers of paper 
and cotton goods are often sensible of this fact, by expe- 
rience. 

It appears, on experiment, that when bleaching powder is 
kept for a considerable time, even in a properly secured 
vessel, such as glass bottles well corked, that it still slowly 
undergoes the same change, which is immediately effected 

Explain the chemical changes which take place when chloride of lime is 
decomposed by heat, and converted into muriate of lime. In what manner 
is chloride of lime decomposed, when it is exposed to the atmosphere? On 
what does the bleaching property of the chloride depend ? What quantity 
of chlorine is lime capable of absorbing ? According to Dr. Ure, what does 
the bleaching powder of commerce contain besides the chloride of lime ? 
What kind of decomposition does bleaching powder slowly undergo whQU 
confined in close vessels ? 



260 CHLORIDE OF LIME. 

by heal, as described above. This seems to be in conse- 
quence of the superior affinity of chlorine for the calcium. 
or the metallic basis of the lime, by which the oxygen is 
slowly disengaged, and a chloride of calcium, or muriate of 
lime, is formed, and thus the bleaching power is in process 
of time entirely destroyed. 

473. The principal expense of manufacturing chloride of 
lime, being that of the chlorine itself, and there being no 
method of ascertaining its quantity, except by experiment, 
the purchaser generally has to depend chiefly on the hon- 
esty of the manufacturer, for the goodness of the article, 
even when recently made. But as there are several causes 
of decomposition, even when it is honestly and carefully 
made, the buyer is still liable to be deceived, unless he makes 
his experiment before the purchase. 

Under such circumstances, the English chemists have 
devised several simple methods of testing the quality of 
bleaching powder, in order that the buyer might judge of 
its goodness without actual trial at home. 

474. Test for chloride of lime. — One of these methods is, 
to expose the salt to a sufficient degree of heat to expel the 
oxygen from the lime, and by measuring its quantity, to 
judge of the quantity of the chloride of lime. The quantity 
of oxygen thus expelled, indicates the quality of the bleach- 
ing powder, so far only as regards the quantity of muriate 
of lime with which it is mixed ; for, as above stated, the 
base of the chloride contains oxygen, while the muriate con- 
tains none. But in addition to the imperfection of this 
method in not indicating the actual quantity of chlorine pre- 
sent, there is much difficulty in ascertaining the quantity of 
oxygen by it, since various proportions of chlorine might 
also be disengaged by the heat, along with the oxygen. This 
method cannot, therefore, be readily or generally employed, 

475. It has also been proposed, to analyze the powder by 
nitrate of silver. But this test only indicates the quantity 
of muriate of lime, by forming with the muriatic acid an in- 
soluble chloride of silver. This test is therefore useless. 

Several other methods have been tried, and among them, 
*hat of destroying the color of a certain quantity of indigo 
nas been most employed. 

On what principle has it been proposed to ascertain the goodness of bleach- 
ing powder by the quantity of oxygen it contains ? How is the goodress of 
bleaching powder tested by means of a solution of indigo ? 



PHOSPHURET OF LIME. 261 

A known quantity of indigo being in solution, a certain 
fiuinoer of grains of the powder is added, and the strength 
ol the latter ascertained by the amount of coloring matter 
destroyed, or by the number of grains required to discharge, 
entirely, me color of a certain quantity of indigo. 

This meiliod has the advantage of simplicity, but is de- 
fective in otner respects, and particularly so in regard to the 
difference m the quantity of coloring matter in different 
kinds or specimens of indigo. 

The most accurate method is to decompose the chloride 
of lime confined in a glass tube, over mercury, by means of 
muriatic acid. The chloride, by this means, would only be 
decomposed, and converted into the muriate of lime, while 
the muriate already formed, would remain as before. By 
this process the chlorine of the chloride is set free, unmixed, 
and its quantity readily measured by the tube in which the 
experiment is made. 

There being no standard of the quantity of chlorine w^hich 
the best bleaching powder ought to contain, it is by the com- 
parison of different specimens only, that the purchaser can 
be guided. 

476. Disinfecting property of Chloride of Lime. — Experi- 
ments have long since shown, that chlorine has the power 
of combining with, or in some other manner, neutralizing, or 
destroying, the fetid exhalations arising from putrefying sub- 
stances, and of preventing their deleterious effects. In cases 
of infectious disease, therefore, it is highly useful. For this 
purpose, a table spoonful or two of the powder is mixed with 
a pint of water, and placed in the sick room, and sprinkled 
in the rooms adjoining. The fetid effluvia from putrid water, 
from sink drains, or from any other source, is immediately 
destroyed by the application of a quantity of the chloride. 

By placing a sheet, wet w4th the chloride of lime water, 
in the bottom of the coffin, and afterwards often sprinkling 
the shroud with the same, the bodies of the dead may be 
preserved without offence for many days in the hottest 
season. 

477. Phospliuret of lime. — This compound is formed by 
passing the vapor of phosphorus over fragments of quick- 

What is the defect in this method? What is said to be the most accurate 
method of ascertaining the quantity of chloride in bleaching powder? Is 
there any standard of the strength of bleaching powder? What is said 
of the disinfecting power of chlorine ? What is phosphuret ©f lime ? 



262 METALS. 

lime, at a red heat. The experiment may be performed in 
viie foUowmg manner : 

Having procured a tube of green glass about a foot and a 
half long, and half an inch in diameter, stop one end with a 
cork, or otherwise, and place in it a drachm of phosphorus, 
letting it occupy the closed end. Then holding the tube in 
a horizontal position, push into it with a wire, or rod, pieces 
of fresh burned quicklime about the size of peas, until they 
fill the middle part of the tube, taking care that the lime 
does not reach the phosphorus by two inches. Then stop 
tae mouth of the tube loosely, to prevent the free access of 
the air, but leaving room for that in the tube to pass out as 
it expands. 

Next, heat that part of the tube containing the lime red 
hot, by means of a chafing dish of coals, at the same time 
keeping the phosphorus cool by a wet rag passed round the 
end of the tube. When the lime is seen to be at a red heat, 
bring a hot iron, or lamp, under the phosphorus, which will 
soon be turned into vapor, and passing over the lime, the 
two substances combine, and form the phosphuret of lime. 

When phosphuret of lime is thrown into water, mutual 
decomposition ensues, and there rises bubbles of phosphu- 
retted hydrogen through the fluid, which take fire on reach- 
ing the air. The phosphorus absorbs the oxygen from the 
water, thus liberating the hydrogen, which combines with a 
portion of phosphorus, forming the gas above named. 

ORDER II. 

Metals which are supposed to be analogous to order 1st. 
They are the metallic bases of the earths. These are, 
Magnesium, Yttrium, and 

Glucinum, Aluminum, Zirconium. 

478. Magnesia, glucina, yttria, alumina, and zirconia, 
before the galvanic experiments of Sir H. Davy, have been 
known under the general name of earths, and were consid- 
ered pure elementary substances. When these earths are 
submitted to the action of a powerful galvanic battery, they 
all give m.ore or less evidence that their bases are metals, 



i 



Describe the process of making the phosphuret of lime. When phosphuret 
of lime is thrown into water, what are the chemical changes produced ? What 
xs the definition of order 2d. ? What are the names of the substances belong- 
ing to order 2d. ? Under what names were these substances known before 
the experiments of Sir H. Davy ? 



EARTHS. 263 

combined with oxygen. Magnesia, for instance, when ex- 
posed for a long time to the action of a powerful battery, in 
contact with mercury, appears to be decomposed ; for the 
mercury becomes enlarged in bulk, and losing its fluidity, 
shows signs of having formed an amalgam with the metallic 
base of the magnesia. When this amalgam is heated in a 
close vessel, out of contact with the air, the mercury is driven 
off, and there remains a dark gray film, of a metallic ap- 
pearance, which, when exposed to the action of oxygen, is 
converted into a white powder, having the properties of mag- 
nesia. It is therefore concluded, that magnesia has a me- 
talhc base, though the metal itself has never been separated 
in such quantities as to allow any further examination of 
Us properties than those above stated. 

When the earth alumina^ which is the base of alum, is 
brought into contact with the vapor of potassium at a white 
heat, and in a close vessel, the potassium is converted into 
potash. Now, as potassium is converted into potash only 
by the absorption of oxygen, and as the oxygen could have 
been derived from no other source except the alumina, such 
an experiment shov/s that alumina contains oxygen, and 
therefore by analogy, there is reason to suppose that alumina 
is composed of the metal aluminum and oxygen. 

479. The other earths above named, when submitted to 
similar experiments, have each shown that they contained 
oxygen ; and as potash, soda, and lime, are known to be 
metallic oxides, that is, to consist of a metal combined with 
oxygen, it is inferred that the earths, possessing similar pro- 
perties, are also composed of a metal united with oxygen. 
It is therefore agreed among writers on chemistry, that the 
bases of these earths should be arranged as metals, under 
the names above specified ; though their existence, with 
perhaps the exception of magnesium, has never been directly 
proved. 

In consequence of the discovery, or the inference, that the 
earths possess metallic bases, their names, in conformity 
with the language of chemistry, are changed from words 
denoting simple bodies, to such as denote compounds. Thus, 

"Were they formerly considered compound, or elementary bodies ? What 
is the reason for supposing that magnesia has a metallic base ? What is the 
reason for supposing that alumina has a metallic base ? On what grounds is 
it believed that the other earths belonging to this order have metallic bases ? 
What are the scientific names of magnesia and alumina, supposing them to be 
the oxides of metals "^ 



264 METALS. 

the earth formerly called magnesia, is now known under tho 
name of oxide of magnesium^ and the simple term alumina. 
is changed to oxide of aluminum^ the same language being 
adopted with respect to all the other earths above named. 

PROPERTIES OF TilE EARTHS. 

480. Magnesia^ or oxide of Magnesium. — Pure magnesia 
is well known as a medicine, under the name of calcined 
magnesia. This is obtained bj exposing the carbonate of 
magnesia to a red heat. It is white, tasteless, and inodorous, 
but possesses slight alkaline properties, being capable of 
changing t^e blue colors of vegetables to green, and of neu- 
tralizing the acids, with which it forms various saline com- 
pounds. One of these, the sulphate of magnesia, or Epsom 
salt, is a well known medicine. 

Magnesia, in a few instances, has been found m the na- 
tive state, but always in small quantities only. That sold 
by apothecaries is obtained from certain springs, as thai o' 
Epsom, where it exists, in combination with sulphui'C acid, 
forming Epsom salt, which is dissolved in the water. 

Calcined, or pure magnesia, if exposed to the air, absorbs 
carbonic acid, and is converted into a carbonate. Hence, 
a large proportion of that used in medicine, and sold for 
calcined, is in truth the carbonate, the change being effected 
by carelessness, in exposing the calcined to the air. 

481. Alumina, or Oxide of Aluminum. — The earth 
alumina is one of the most abundant productions of nature, 
every description of clay being an aluminous earth, of a 
greater or less degree of purity. The claj^ of which bricks, 
pipes, and earthen w^are are made, consists chiefly of this 
earth. The ruby and the sapphire, two of the hardest and 
most beautiful of gems, are also composed of alumina. 
Pure alumina, for experiment, is most easily obtained from 
alum, which is a sulphate of alumina and potassa. To 
obtain the earth, dissolve one part of alum in six parts o1 
boiling water, and when the solution is cold, add one pait 
of carbonate of potash. By this process the sulphate of 
alumina is decomposed, in consequence of the strong 

How is pure magnesia obtained? What effect does magnesia have on 
vegetable colors ? What is the most common salt of which magnesia is the 
base ? How is pure magnesia converted into a carbonate ? How is the un- 
certainty of magnesia, as a medicine, accounted for ? What is the earth oJ 
which clay is chiefly composed ? What common articles, and what precious 
stontts, are composed of alumina? How may pure alumina be obtained ^ 



METALS 265 

affinity existing between the ["xitash and sulphuric ?.cicl. 
and two new salts are formed, viz. sulphate of potash and 
carbonate of alumina, the latter being precipitated to the 
bottom of the vessel. This precipitate loeing washed, and 
then exposed to a red heat, to expel the carbonic acid, is 
p. ire alumina. 

The substance, thus procured, is white, inodorous, soft 
to the touch, and tasteless. Mixed with water, it forms a 
mass which is exceedingly plastic, and may be worked 
into all shapes. The tenacity of every kind of clay is 
owing to the alumina it contains. 

Alumina, being insoluble in water, does not affect the 
colors of vegetables. It, however, performs the part of an 
alkali in neutrahzing the acids, and forming with them sa- 
line compounds. 

482. Glucina, or Oxide of Glucinum. — The earth called 
glucina has been discovered but in small quantities, being 
known to exist only in the minerals, emerald, beryl, and 
euclase. Its name comes from a Greek word signifying 
sweet, because some of its combinations are sweet to the 
taste. In some of its properties it resembles alumina, and 
in others it differs from all the other earths. One of its dis- 
tinctive properties is that above mentioned, of forming a com- 
pound, when dissolved in sulphuric acid, which is sweet to 
the taste. 

483. Yttria^ or Oxide of Yttrium. — Yttria resembles alu- 
mina and glucina in most of its chemical properties, but 
differs from them both, in being insoluble in a solution of 
pure potash. This earth has been found only in a single 
rare mineral, in Sweden. It forms peculiar salts, when 
combined with the acids, and is thus known to differ from 
all the other earths. 

484. Zirco7iia, or Oxide of Zirconium. — This earth is also 
exceedingly rare, having been detected only in the zircon, a 
precious stone found in Ceylon, and the hyacinth of France. 
It resembles alumina and the other earths in being a white 
scift powder. Its salts are distinguished by being precipi- 
tated from their solutions by all the pure alkalies. 

What chemical changes take place when alum, in solution, is mixed with 
carbonate of potash? What is the appearance of pure alumina? In what 
minerals does the oxide of glucina exist? What is the meaning of the word 
glucina, and why is this earth so named? How does yttria differ from alu- 
mma and glucina? In what minerals has the earth zirconia been found? 
How are the salts of zirconia distinguished ? 
12 



■HHiHiaillMlHl 



266 METALh. 

Ziiconium, the base of this earth, was separated from its 
oxygen, by the Swedish chemist Berzehus, in 1824. It 
was in the form of a black powder, which took fire in the 
open air at a temperature far below a red heat, and burned 
with a bright flame. The product of the combustion was 
zirconia. But whether this base is of a metallic nature, has 
not been decided. It is wanting in one property common to 
all metals, being a non-conductor of electricity. 

485. Silica^ or Oxide of Siliciwn. — Sir H. Davy's experi- 
ments on silica led him to suppose, that in common with 
the earths above described, it had a metallic base, and it 
was arranged with them, in conformity to this opinion. But 
more recently, Berzelius has succeeded in decomposing this 
earth, and has given an account of the properties of its base. 
From this we learn that siHcium. is of a dark brown color, 
without the least trace of a metallic lustre. That it is in- 
combustible in the open air, or in oxygen gas, and that it 
may even be exposed to the flame of the blowpipe without 
fusion, and without suffering the least change. It is not 
dissolved by any of the acids, except a mixture of the nitric 
and fluoric, with which it readily enters into solution. It is 
not a conductor of electricity. These properties, and particu- 
larly its want of metallic lustre, and of power to conduct elec- 
tricity, prove that the base of silica is not of a metallic nature. 

486. Silica, or silex, is a very abundant natural product. 
It forms a large part of all granitic, or primitive rocks, and 
mountains, and is the chief ingredient in sandstones, and 
earthy formations. Rock crystal, or quartz, flint, chalce- 
dony, agate, cornelian, and all other substances of this kind, 
are composed almost entirely of silex. 

487. Sihca may be obtained in sufficient purity for most 
purposes, by heating transparent rock crystal to redness and 
plunging it into water while hot, and then reducing it to 
powder. 

488. In this state, silex is a white powder, which feels 
harsh when imbbed between the fingers, and has neither 
taste nor smell. It is exceedingly infusible, but may be 
melted with the compound blowpipe. It resists the action 
of all the acids, except the fluoric, which dissolves it with 
considerable facilitj^ It is dissolved by the fixed alkahes, 

What is said of the metallic base of zirconia ? What is said of the metallic 
base of silica"? Is the base of silica of a metallic nature ? What substances 
are mentioned of which silica forms the principal part ? How may pure silica 
be obtained ' What are the properties of silica? 



METALS. 267 

and hence it would appear that its properties are rather of 
an acid, than of an alkahne nature. On this account 
several chemists have called silica an acid, and the com 
pounds which it forms with the alkalies, have been termed 
silicates. 

From what has been said, the student will infer that there 
is yet considerable doubt and uncertainty, in respect to the 
real nature of silica. 

Dr. Thompson, being convinced of its non-metallic nature, 
arranges it with the simple bodies carbon and boron. There 
is no doubt, however, from the experiments of Davy and 
Berzelius, of its compound nature ; and that it consists of 
a base combined with oxj^gen, has been proved by direct 
experiment. But that its base is not a metal is proved from 
its want of lustre, and power to conduct the electric fluid, 
those two properties being essential to all metallic bodies. 

489. Silex in the form of sand, is a principal article in the 
manufacture of glass. The common dark colored, or green 
glass, is composed of impure sand, which contains oxide 
of iron, melted with kelp, wood ashes, or impure potashes. 
Crown glass, for windows, is composed of white sand, fused 
with a purer alkali. Plate glass, for looking glasses, is 
made of still purer m-aterials ; and what is known by the 
name of flint glass, of which decanters, and other ornamen- 
tal, or cut glassware is made, is composed of the purest sand 
and alkali, with the addition of a considerable portion of 
lead, which is added in the form of litharge, or red lead. 
This is the softest and heaviest kind of glass. It cuts more 
easily, and withstands the changes of temperature much 
better than glass containing no lead. 

ORDER III. 

Metals which decompose water at a red heat. These are^ 

Manganese, Iron, and 

Zinc, Tin, Cadmium. 

Cobalt, Nickel, 

490. The power of a metal to decompose water, depends 
on its affinity for oxygen. In some instances, as in those of 

What is said of the compound nature of silica ? What use is made of 
silex in the arts? Explain the difference between green glass, crown glass, 
and plate glass. What is the composition of cut glass ? What is the defini- 
tion of order 3d ? What metals belong to order 3d ? On what property ot 
a metal does its power to decompose water depend ? 



2r)f5 METALS. 

potassium and sodium, already given, the metals have so 
strong an affinity for oxygen, as to absorb it from water, al 
common temperatures. Other metals do not decompose this 
fluid at any temperature, such being the 4th order of the 
present class. Those now to be examined have an affinity 
for oxygen, which they slowly absorb from the atmosphere, 
and a part of which they retain at high degrees of heat. 
But theh attraction for oxygen is not in sufficient force to 
decompose water, except when heated to redness, when the 
combination is effected with considerable rapidity. 

MANGANESE, 28. 

491. This metal always occurs in nature in combination 
with oxygen, and which it holds with such force as to re- 
quire the most intense heat for its removal. The metal may, 
however, be obtained in a pure state, by exposing the black, 
or peroxide, mixed with a combustible, to the highest heat 
of a smith's forge. The combustible, which may be pitch, 
or powdered charcoal, with which the oxide is mixed, is 
thus made to absorb the oxygen, and the metal is found at 
the bottom of the crucible. 

Manganese is of a dusky white color, with a specific 
gravity of 8. When exposed to the air it absorbs oxygen, 
and soon falls into powder, which afterwards changes its 
color from gray to brown, and from brown to black, accord- 
ing to its grade of oxidation. When this metal is exposed 
to a red heat, and the steam of water is passed over it, de- 
composition takes place, the oxygen of the water combines 
with the manganese, and the hydrogen is disengaged. 

MANGANESE AND OXYGEN. 
PEROXIDE OF MANGANESE, 44. 

1 eq. Manganese, 28 + 2 eq. Oxygen, 16. 

BLACK OXIDE OF MANGANESE. 

492. This compound occurs abundantly in nature, and is 
known under the name of black oxide of manganese. It is 
found in amorphous masses, of a dark gray or nearly black 
color, and is commonly mixed with various proportions of 

In "what state does manganese occur in nature ? By what process may 
metallic manganese be obtained from the oxide? What is the appearance 
and specific gravity of manganese ? Under what circumstances does man- 
ganese decompose water ? What is the scientific name for black oxide of 
manganese ? 



METALS. 269 

sand, oxide of iron, carbonate of lime, or other impurities. 
In its pure state, it occurs in the form of prismatic crystals, 
of a dark color, and shghtly metaUic lustre. 

In this state the metal contains its full proportion of oxy- 
gen, and undergoes no change on exposure to the air, or to 
a moderate heat. When heated to redness, it parts with 
one proportion of oxygen, and is converted into a deutoxide. 
In this manner oxygen gas may be obtained. The per- 
oxide of manganese is of considerable consequence in the 
arts, and particularly in the formation of chlorine for the 
manufacture of bleaching powders, and also in furnishing 
oxygen gas for other chemical uses. The methods for ob- 
taining these gases have already been described. 

The peroxide of mercury is composed of 

1 proportion of manganese, 28 

2 proportions of oxygen, 16 

44 

There are two other oxides of manganese, viz. the pro' 
toxide, and the deutoxide. There is also reason to believe 
that manganese is capable of combining with such pro- 
portions of oxygen as to form acids ; but the subject has not 
been sufficiently investigated to determine the composition 
or nature o( these compounds. 

Manganese combines with the acids, and forms a variety 
of salts, which are either colorless, or of a reddish or pink 
hue. These salts are found only in the laboratory of the 
chemist, and are of no use in the arts. At a red heat this 
metal decomposes water. 

IRON. 

Equivalent, 28. 

493. This well known metal has a gray color, and a 
strong metallic lustre, which is much improved by burnish- 
ing. Iron is at once the most useful, the most abundant, 
and the most universally diffused of all the metals. It is 
found in the mineral, the vegetable, and the animal king- 
doms, and in some countries it exists in such quantities as to 
form mountains of considerable size. 

When peroxide of manganese is heated to redness, what chemical change 
does it undergo ? Of what use is peroxide of manganese in the arts ? What 
is the composition of the peroxide of manganese ? What is said of the acids 
of manganese ? What is the combining number for iron ? 



270 METALS. 

When heated, it becomes soft and malleable, and in this 
state two pieces may be incoi-porated, or welded together, 
by hammering. Its specific gravity is about 8. It is at- 
tracted by the magnet, and may itself be made permanently 
magnetic. This property is of vast consequence to the 
world, being possessed by no other metals except nickel, and 
cobalt, and by these in a much inferior degree. 

Iron has a strong affinity for oxygen, and when exposed 
to air and moisture, soon rusts or oxidates on its surface. In 
a perfectly dry atmosphere, however, it undergoes little or 
no change, a proof that it absorbs oxygen with more facility 
from water than from the air. When heated, it attracts 
oxygen both from air and water, with great rapidity. When 
the steam of water is passed over iron, at a red heat, the 
water is decomposed, its oxygen combining with the metal, 
while the hydrogen is set at liberty. When heated to red- 
ness, in oxygen gas, it burns with intense brilhancy. Iron 
is exceedingly ductile, and may be drawn into wire not ex- 
ceeding the thousandth part of an inch in diameter ; but it 
cannot, like gold and silver, be hammered into thin leaves, 
and therefore is not highly malleable. 

The ores of this metal are very numerous, and some of 
them highly beautiful and interesting. They are chiefly 
sulphurets and oxides, but the oxides are the only ores from 
which the metal is obtained. 

Iron has, in a few instances, been found in its native state, 
mixed with lead and copper, or with some earthy substance. 
It has also been found in large masses, alloyed with five oi 
six other metals, and called meteoric iron^ from an opinion 
that these masses fell from the clouds. Native iron is soft 
and malleable as it occurs, and does not differ from that 
which has been reduced from its ores and purified. 

Cast iron contains variable proportions of carbon and oxy- 
gen, and in this state it is hard and brittle. These impuri- 
ties are detached by the process of refining, and then the 
iron becomes soft and malleable. 

Steel is made by heating pure iron with carbon, or char- 

What is said of the abundance and usefulness of iron ? "UTiat is said of 
the affinity of iron for oxygen ? Under what circumstances does iron de- 
compose water ? In what does this decomposition consist ? What is said 
of the ductility and malleability of iron ? In what state does iron occur as a 
natural product? What is the ore from which iron is extracted? WTiat is 
meteoric iron ? What are the impurities contained in cast iron ? How is 
stee* made ? 



METALS. 271 

- aI, by which it is rendered exceedingly hard and brittle. 

4 nis change is produced in consequence of the absorption 
vi ix portion of carbon by the iron. Steel, therefore, is com- 
posed of iron and carbon, and its scientific name is carburet 
of iron. 

IRON AND OXYGEN. 
OXIDE OF IRON. 

RUST OF IRON. 

494. Iron combines with oxygen in two proportions, form- 
ing the blue and red oxides of this metal. 

495. Protoxide of Iron. — The black, or protoxide of this 
metal, is formed by passing dry hydrogen over the red oxide, 
at a temperature a little below redness. This oxide is com- 
posed of 1 equivalent of iron 28, and 1 equivalent of oxygen 
8. Its combining number, therefore, is 36. 

496. The Black Oxide of Iron^ which occurs in the form 
of scales, when iron is heated and hammered in the open 
air, is not a definite compound, but a mixture of the black 
oxide and metalhc iron. 

497. Peroxide of Iron. — This is the red oxide, and is 
known to mineralogists as a native compound, under the 
name of red hematite. The same article is known to button 
makers, and other artists, under the name of blood stone^ 
and is employed to polish their work. The peroxide may 
be prepared by art, by dissolving iron in nitric acid, then 
precipitating it with ammonia, and heating the precipitate 
to a little below redness, to drive off the acid. Its color and 
other properties are like those of the native red oxide. The 
peroxide of iron is composed of iron 28, and oxygen 12. 

498. The Brown Oxide of Iron is composed of precisely 
the same proportions of the metal and oxygen as the red 
oxide, but in addition to these ingredients, it contains one 
proportion, or 9 parts of water. 

The other oxides of iron are either mixtures of the red and 
blue oxides, or one or both of these oxides containing various 
impurities. The great number of oxides of this metal, de- 
scribed in books of mineralogy, and differing from each other 



What is the composition of steel ? What is the scientific name of steel '' 
[n how many proportions does oxygen combine with iron ? What are the 
names of these oxides ? What is the composition of the protoxide ? What 
is the composition of the peroxide of iron ? How does the brown differ from 
'iie red oxide of iron "^ 



272 METALS. 

in color, hardness, and form, arise from such mixtures 
Thus, the magnetic oxide of non, or native magnet, is com- 
poz:ed of peroxide of iron 71, and protoxide 29 to the 100. 
The brown oxides of iron all contain water, and are, there- 
fore, called hydrates. The ochres are of this kind. 

Iron combines with carbon, sulphur, iodine, phosphorus, 
and the different acids. Its compounds are, therefore, ex- 
ceedingly various, in respect to form, color, and properties. 
We shall, however, examine only two or three of these com- 
pounds here, the salts being reserved for another place. 

499. Carburet of Iron. — Steel, we have already said, is a 
carburet of iron. This important metal is manufactured 
from the iron, by exposing the latter to a long continued red 
heat, in contact with charcoal. For this purpose, the purest 
malleable iron, in bars, is employed, and is found to gain in 
weight, one pound in 150, by the process. Steel, therefore, 
consists of iron combined with a 150th part of its weight of 
carbon, which it absorbs from the fire. When iron is per- 
fectly enclosed, and heated with a fragment of diamond, it 
is converted into steel, in the same manner as when heated 
with charcoal. This experiment shows the identity of car- 
bon and diamond, the only difference being the color and 
crystaline form of the latter. It also proves that the hard- 
ness of steel is owing to the particles of diamond which it 
contains. 

The native carburet of iron, commonly known under the 
name of black lead, or plumbago, contains 95 parts of carbon 
and 5 of iron. This substance is infusible at the highest 
heat of a furnace, and hence is employed in making cruci- 
bles and melting pots. It is also used in making black lead 
pencils. 

500. SulpJiuret of Iron. — This compound occurs as a 
natural product, and is known to mineralogists and others, 
under the name of iron pyrites. It is a yellow brittle 
substance, often crystalized in the form of cubes, or octo- 
hedrons, with their surfaces highly polished. These 
specimens are generally taken for gold, by those who are 

What is the composition of the native magnet? What substances are 
mentioned with which iron combines? In what proportion is the weight of 
iron increased by being converted into steel? What is said of converting 
iron into steel by means of the diamond ? What does this experiment prove ? 
What is the composition and the proper name of black lead ? What are the 
uses of black lead? Is sulphuret of iron a natural, or artificial compound? 
What is the appearance of the native sulphuret of iron? What precious 
metal is this compound sometimes taken for ? 



METALS. 273 

ignorant of such matters, and the places where they are 
found are sometimes kept a profound secret, for years, for 
fear the owner of the soil should claim a part of the wealth. 
Every mineralogist, on pronouncing such specimens of no 
value, has occasionally witnessed the fallen countenance of 
the applicant, whose hopes and expectations he had thus 
blasted. Sulphuret of iron may also be formed by touching 
a bar of iron, at a glowing red heat, with a roll of brim- 
stone. The compound will fall down in drops. The 
natural and artificial sulphurets are composed of precisely 
the same definite proportions, viz. iron 28, and sulphur 16. 



Equivalent, 32. 

501. Zinc, when pure, is of a bluish white color, and ol 
a striated fracture, presenting the result of a confused crys- 
tahzation. When rubbed with the fingers it imparts to 
them a peculiar metallic taste and smell. When cold, this 
metal is not malleable, but when heated to between 200° 
and 300°, it becomes both malleable and ductile. If its 
temperature be raised to 400°, it becomes so brittle as to be 
readily reduced to powder, in a mortar. 

Zinc melts at 680°, and if this temperature be increased, 
it burns with a bluish flame in the open air. When melted 
with copper it forms the alloy, well known under the name 
of brass. 

502. This metal never occurs in the native, or pure state 
but is alwaj^s found combined either with sulphur, carbonic 
acid, or oxygen. The sulphuret of this metal, called zim 
blende^ and the carbonate, called calamine^ are the ores from 
which zinc is obtained. The sulphuret being roasted^ that 
is, submitted to a low red heat in the open air, to drive off 
the sulphur, and oxydize the metal, is then melted with 
charcoal, by which the oxygen is absorbed, and the metal 
reduced. The calamine is first roasted to drive off' the car- 
bonic acid, and is then distilled in iron retorts, by which 
means the pure metal is obtained. This latter process is 
said to have been learned of the Chinese, and that a man 



How may sulphuret of iron be formed artificially ? What is the composi 
tion of sulphuret of iron 1 What is the color of pure zinc ? Under what 
circumstances is zinc malleable? In what temperature does zinc melt? 
What is the composition of brass ? Is zinc ever found in the native state ' 
What are the names of the ores of zinc, and of what are they composed ? 
How is zinc reduced from its sulphuret? How is calamine re/duced? 
12* 



274 METALS. 

was sent fiom Europe to China on purpose to obtain the 
secret. Pure zinc, when exposed to a white heat in a close 
vessel, will in the same manner sublime, and again con- 
dense, unchanged. 

ZINC AND OXYGEN. 
OXIDE OF ZINC, 40. 

1 eq. Zinc, 32+1 eq. Oxygen, 8. 

FLOWERS OF ZINC. 



503. When zinc is exposed to a red heat in the open air, 
it burns with a white flame, and at the same time an oxide 
of the metal is formed, which rising by the heat falls around 
the place of combustion in the form of white flakes. This 
substance was formerly called flowers of zinc^ and some- 
times philosophical wool. It is an oxide of the metal, and 
the only one known. When this oxide is collected, and 
again submitted to the fire, it does not rise, as before, but 
melts into a clear glass. 

When the vapor of water is brought into contact with 
metallic zinc at a red heat, the water is decomposed, the zinc 
combining with its oxygen, and foiming an oxide, in the same 
manner as is done in the open air. Both these oxides are 
composed by weight of 

1 equivalent of zinc, 32 

1 do. oxygen, 8 

Combining number for oxide of zinc, 40 
c A D M I u ai . 

EQUIVAL ENT, 56. 

504. Cadmium is one of the new metals, having been dis- 
covered in certain ores of zinc, in 1817. This metal in 
color and lustre resembles tin, but is harder and more tena- 
cious. It is both ductile and malleable to a considerable 
degree. Its specific gravity is nearly 8.5. It fuses at a 
temperature something less than 500°, and at a little higher 
heat it rises in vapor, and condenses in globules like mercury. 



How is the oxide of zinc formed? What was this oxide formerly called? 
How may zmc be made to decompose water? What is the composition of 
oxide of zinc, and what is its combining number ? What is cadmium ? What 
other metals does cadmium resemble ? Is this a brittle or a malleable metal? 
What is the specific gravity of cadmium? 



TIN. 276 

^ hen cadmium is heated in the open air, Hke many other 
iM€/tals, it absorbs oxj-gen, and is converted into an oxide. 
It IS readily dissolved by the nitric acid. When heated in 
contact with the vapor of water, the fluid is decomposed, 
and an oxide of the metal is formed. 

Cadmium combines, so far as is known, with only one 
proportion of oxygen. This oxide is composed of 
Cadmium, 1 equivalent 56 
Oxygen, 1 do. 8 

64 

Cadmium, like the other metals, forms salts by combina- 
tion with the acids. But these compounds are httle known, 
and of no value. 



Equivalent, 58. 

505. Tin must be examined in the state of grain, or block 
tin; what is commonly called tin, being sheets of iron, 
merely covered with this metal. 

Tin is procured from its native oxides, by heat and char- 
coal, on the same principle that has already been described 
for iron and several other metals. The ores of tin are only 
two, viz., an oxide, and a sulphuret. This metal is not read- 
ily oxidized by exposure to the atmosphere, though the brill- 
iancy of its surface is soon tarnished. It is highly mallea- 
ble, but not equally ductile, its tenacity not being sufficient 
to allow its being drawn into fine wire. Its specific grav- 
ity is 8. When heated to whiteness, it takes fire in the open 
air, and burns with a white flame, being at the same time 
converted into an oxide ; at a red heat it decomposes water. 

Tin is a highly useful metal, being employed for many 
valuable purp nses in the arts and conveniences of life. Thin 
sheets of iron, being dipped into melted tin, receive a coat of 
the metal, and are thus prevented from rusting. This is 
called sheet tin^ and is the article of which the common tin 
ware is made. Tin foil, that is, tin rolled into thin sheets, is 

Wliat is the composition, of oxide of cadmium? Of what metal is the sheet 
tin chiefly composed ? How is tin procured from its oxide ? What are the 
only ores of tin? Is tin readily oxidized by exposure to the air or not? 
What is said of the malleability and ductility of tin? What is the specific 
gravity of tin ? Into what is this metal converted when burned in the opcu 
air ? How is sheet tin made ? What are the principal uses of tin ? 



I 



276 TJN. 

used for many purposes. Electrical jars are coated with it 
and the backs of looking-glasses are formed of an amalgan 
of tin foil and mercury. Block tin forms a part of 3ritan 
nia ware, of princes' metal, of pewter, speculum metal, &c 

TIN AND OXYGEN. 

506. Tin combines with oxygen in two proportions : Th 
first, or the protoxide, is formed when the metal is kept foi 
some time in fusion in the open air. At this temperature it 
absorbs oxygen from the atmosphere, and is converted into 
a gray powder. This powder is the protoxide, and is com 
posed of 

1 equivalent of tin, 58 
1 do. oxygen, 8 

66 

This oxide is soluble in acids and in ammonia. The sec- 
ond, or peroxide of tin, is prepared by dissolving the metal 
in nitric acid, shghtly diluted with water. It is a powder of 
a yellow color, and is composed of 

1 equivalent of tin, 58 

2 do. of oxygen, 16 

74 

This oxide, when melted with glass, forms white enamel. 

Tin combines with sulphur, chlorine, and the acids, form- 
ing a variety of compounds, some of wliich are occasionally 
used in the arts. 

ORDER IV. 

507. Metals ivkich do not decompose water at any tempera 
ture. These are, 

Arsenic, Uranium, Copper 

Molybdenum, Columbium, Tellurium, 

Chromium, Cerium, Lead, 

Tungsten, Titanium, and 

Antimony, Bismuth, Vanadium. 

The last order includes all such metals as attract oxygen 

In how many proportions does tin coinbine with oxygen ? How is the pro- 
toxide of tin formed ? What is the composition of the protoxide of tin ? How 
is the peroxide of this metal prepared ? What is the quantity of oxygen con 
tained in the peroxide of tin ? What is the definition of order 4ih ? What 
are the names of the metals arranged under the 4th ordc ? 



ARSENIC. 277 

with sufficient force, when heated to redness, to decompose 
water. The present division absorb and retain oxygen at 
high temperatures, but none of them attract that principle, 
even at the highest temperatures, with sufficient force to 
decompose water. 

ARSENIC. 

Equivalent, 38. 

508. There are no mines worked merely for the purpose 
of obtaining arsenic, the arsenious acid, the only form in 
which it is used, being procured by the process of roasting 
the ores of cobalt. The ores of the latter metal, being 
heated in furnaces with long chimneys, the acid rises and 
attaches itself to the sides of the chimney, in layers, or 
cakes. After a considerable quantity has been accumu- 
lated in this manner, it is scraped off, and purified by a 
second sublimation, when it forms the well known poison 
called white arsenic^ or oxide of arsenic. 

From the white oxide the metallic arsenic is procured, by 
heating this with a combustible. 

509. In legal investigations, where there is a suspicion of 
poisoning with arsenic, it sometimes happens that justice 
will depend on the decision of the chemist, whether arsenic 
might not have been the cause of death. In such cases, 
very minute portions of arsenic may be detected by means 
of a combustible and a glass tube, in the following manner: 
Let the matter suspected to contain the poison, be well dried 
at a low heat ; then mix it with five or six times its weight 
of powdered charcoal, and put the mixture into a thin glass 
tube, closed at one end. If now heat be gradually applied 
to the tube until it becomes red, the metal, if arsenic be 
present, will rise and coat its inside, showing a brilliant 
metallic lustre, similar to that of steel. If it is found that, 
on heating a small piece of this metal, it rises in white 
vapor and gives the smell of garlic, it is arsenic beyond 
doubt. 

The structure of metalhc arsenic is crystaline, and its 
specific gravity about 8. When heated to about 360° it 
sublimes, without fusion, its melting point being far above 

Are any mines worked merely to obtain arsenic? How is the oxide of 
arsenic procured ? How may arsenic be reduced from its oxide to the me- 
tallic state ? What is the appearance of pure arsenic ? What is the specific 
gravity of arsenic '^ 



278 METALS. 

that at which it becomes volatile. If the metal is heated in 
the open air, it is converted into the arsenious acid, and 
again oecomes poisonous as before ; but, while in the me- 
tallic form, arsenic has no action on the system, and, there- 
fore, is not a poison. 

ARSENIC AND OXYGEN. 

ARSENIOUS ACID, 54. 

1 eq. Arsenic, 38+2 eq. Oxygen, 16. 

WHITE ARSENIC. OXIDE OF ARSENIC. 

510. We have stated above, that when metallic arsenic 

is heated in the open air, it is converted into a white sub- 
stance called oxide of arsenic. This is the arsenious acid 
of chemists. It differs from the oxides of metals in pos- 
sessing acid properties. It is slightly soluble in water, 
reddens vegetable blue colors, and combines with alkalies, 
forming salts called arseniates. The arsenite of potash, 
usually called Fowler's solution of arsenic, has been long 
emploj'-ed in medicine, as a remedy for eruptive, and other 
diseases. 

ARSENIC AND SULPHUR 

SULPIIURETS OF ARSENIC. 

511. Sulphur combines with arsenic in two proportions, 
forming compounds which are known by the names of orpi- 
ment, and realger. These compounds are both of them nat- 
ural products, and may also be formed by art. Realger is 
of a red, or scarlet color, with a shining semi-metallic lustre, 
and is composed of 38 parts of metallic arsenic, and 16 parts, 
or one proportion, of sulphur. 

Orpiment has a rich yellow color, and a foliated structure. 
Its lustre is shining, and somewhat metallic, and it is read- 
ily separated into layers, hke mica. This is composed of 
3^' parts, or one atom of metallic arsenic, and 24 parts, or 
one atom and a half of sulphur. 

Orpiment is employed as a paint under the name of King's 
Yellow. 



Is metallic arsenic a poison ? How is arsenious acid formed ? WTiat is 
the common name of this acid ? What is the form of arsenious acid? What 
are the salts called which arsenious acid forms with the salifiable bases ? 
What use is made of arsenite of potash ? In how many proportions does sulphur 
combine with arsenic ? What is realger ? W^hat is its composition ? How 
does orpiment differ from realger ? What use is made of orpiment ^ 



CHROMIUM. 279 



CHROMIUM. 

Equivalent, 28 

512. The metal chromium has been detected only in the 
two native compounds, chromate of lead, and chromate of 
iron. In these two salts, the metal chrome exists in combi- 
nation vnX\\ so much oxygen as to constitute an acid, which 
is united to the oxides of lead and iron, forming the com- 
pounds above named. Arsenic, as shown above, forms an 
acid with oxygen in the same manner, and we shall see pre- 
sently that several other metals, when combined with oxy- 
gen, perform the office of acids. 

Chromium has been procured only in very small quanti- 
ties, by exposing its acid mixed with charcoal, to the high- 
est temperature of a smith's forge. It is a brittle metal, of 
a grayish white color, and very infusible. Its specific grav- 
ity is 6. 

Chromium combines with oxygen in three proportions, 
forming the following compounds : 

Chrome. Oxygen. 

Protoxide, composed of 28 and 8 
Deutoxide, do. 28 do. 16 

Chromic acid, do. 28 do. 24 

The oxides of chrome are of no importance in the arts, 
but the chromic acid forms colored salts with the oxides of 
the metals, which are extensively employed in painting and 
coloring. 

The chromic acid may be obtained in a separate state, by 
boiling the native chromate of lead in powder, with twice 
its weight of carbonate of potash, and afterwards saturating 
the alkali with dilute sulphuric acid. The sulphate of pot- 
ash thus formed, will subside, leaving the chromic acid in 
solution, which on evaporation, will yield crystals of chromic 
acid. 

These crystals are of a ruby red color, and when dissolved 
in water, possess all the properties of an acid. 

513. The useful compounds formed by combining chro 



What is chromium ? In what native compound is chromium found ? lit 
what statf; does chromium exist in these compounds ? How has chromium 
been procured? What is the color and what are the properties of chromium? 
In how many proportions does chromium combine with oxygen ? What are 
the names of these compounds ? Of what use is the chromic acid ? How may 
pure chromic acid be obtained? What is the colar and form of this acid"? 



280 CHROMIUM. 

mic acid with salifiable bases, are prepared from chromate 
of potash in solution. The latter salt is made by heating to 
redness the native chromate of iron with an equal weight of 
nitrate of potash. Bj this process, the chromate which was 
in the state of an oxide, is converted into chromic acid, hy 
the oxygen of the nitre, the acid at the same time combining 
with the potash of the nitre. The ignited mass is then dis- 
solved in water, neutralized by nitric acid, and the solution 
concentrated by evaporation. When the chromate of potash 
shoots into crystals, of a yellow color. 

The chromate of lead, a beautiful paint, at present largely 
employed under the name of chrome yellow, is made by mix- 
ing acetate, or sugar of lead, dissolved in a large quantity 
of water, with solution of chromate of potash. A double 
decomposition of these two salts is thus effected, and acetate 
of potash and chromate of lead are formed. The acetate 
remains in solution, while the chromate being insoluble in 
water, falls down in form of an orange colored, or yellow 
powder. This powder being separated from the liquid, and 
dried, forms the beautiful pigment in question. 

MOLYBDENUM. 

Equivalent, 48. 

514. The native sulphuret of molybdenum is a ponder- 
ous mineral, which occurs in masses, or is disseminated in 
other minerals. Its structure is foliated, and its lustre like 
that of lead recently cut. When this compound is reduced 
to fine powder, and digested in nitro-muriatic acid, the sul- 
phur and metal are both acidified by the oxygen imparted 
to them by the nitro-muriatic acid. On heating the solu- 
tion, the sulphuric acid thus formed is expelled, while the 
molybdic acid remains in the form of a heavy white powder. 
From this powder the metalhc molj^bdenum may be obtained 
by exposing it, mixed with charcoal, to the strongest heat 
of a smith's forge. 

This metal has never been obtained, except in very small 
quantities, and in the form of brilliant white globules, con- 
tained in a blackish mass. When heated in the open air, 
'iX is soon converted into molyhdic acid. 

How is the chromate of potash prepared? How is the chromate of lead 
made from the chromate of potash ? What is the color and use of chromate 
of lead ? How is the native sulphuret of molybdenum described ? By what 
process is molybdic acid procured ? How is the metal obtained from this 
ucid? What is the appearance of molybd«num ? 



METALS 2S I 

Moljbdic acid is in the form of a white powder, which 
has a sharp metalhc taste, reddens vegetable hlues, and 
forms salts with the alkalies, called molyhdates. 

This acid is composed of 1 proportion of molybdenum 
48, and 3 proportions of oxygen 24. 

TUNGSTEN. 

Equivalent, 100. 

515. The tungstate of iron, is a brownish black mineral, 
which is found both massive and crystalized. Its specific 
gravity is upwards of 7, and when broken it presents a 
foliated structure, and a lustre somewhat metallic. 

This mineral, by the miners, is called wolfram^ and is 
composed of tungstic acid and oxide of iron, with a portion 
of the oxide of manganese. 

From this mineral the tungstic acid may be procured, by 
the action of muriatic acid, in the form of a yellow powder. 

When tungstic acid is mixed with charcoal, and exposed 
to an intense heat, the metal is deprived of its oxygen by 
the charcoal, and appears in its pure form. 

Tungsten has a specific gravity of 17.4, being next to 
platina, gold, and iridium, the most dense body known. It 
is nearly equal to steel in hardness, and is one of the most 
infusible of the metals. When heated in the open air, it 
is reconverted into tungstic acid. This acid is composed of 
100 parts of tungsten, and 24 parts of oxygen, consequently 
100 is the atomic weight of this metal, and 124 the equiva- 
lent number for tungstic acid. No use has been made of 
this metal, or any of its compounds. 

COLUMBIUM. 

Equivalent, 185. 

516. This metal was discovered by Mr. Hatchett, of Lon- 
don, in a black mineral, which was sent to the British 
Museum by Governor Winthrop, of Connecticut. The 
mineral came from New London, and is said to have been 
found near the residence of the governor. 



What are the salts called which molybdic acid forms with the salifiable 
bases? What is the appearance of tungstate of iron ? How is tungstic acid 
procured? What is the process for procuring tungsten from tungstic acid? 
What is the specific gravity of tungsten ? What are the properties of tung- 
sten? What is the composition of tungstic acid? Whence came the mine- 
ral in which columbiura was first discovered ? 



282 METALS 

Columbium, like tungsten, exists in its natural state, com- 
bined with so much oxygen as to perform the part of an 
acid, and is found united to the oxides of iron, or manga- 
nese. 

This metal is of an iron gray color, and considerable 
metallic lustre. Its specific gravity is 5.5. 

Columbic acid is composed of columbium 185, and oxy- 
gen 8. Its equivalent number, therefore, is 193. 

ANTIMONY. 

Equivalent, 65. 

517. The only ore from which the antimony of com- 
merce is obtained, is the sulphuret. From this native 
compound the pure metal is separated, by heating it with 
half its weight of iron filings in a covei^ed vessel. By this 
process the sulphur unites with the iron, while the fused 
antimony is drawn off at the bottom of the vessel. 

Antimony is a brittle metal, of a bluish white color, and 
considerable lustre. Its structure is lamellated, or it con- 
sists of laj^ers, which are the result of an imperfect crys- 
talization. It fuses at about 800°, and when slowly cooled, 
may be crystalized in octohedrons. By exposure to the air 
it tarnishes, though not so readily as several other metals. 
Its specific gravity is about 7. 

ANTIMONY AND OXYGEN. 

518. Oxygen combines with antimony in three propor- 
tions, forming the protoxide, composed of antimony 65, and 
oxygen 8 ; the deutoxide, consisting of antimony 65, and 
oxygen 12; and the peroxide, composed of antimony 65, 
and oxygen 16. 

The deutoxide combines with alkalies, and forms salts ; 
it is therefore called antimonious acid, and the salts so 
formed are antimonites. 

The peroxide also performs the office of an acid, and 
combines with alkahes, forming salts, called antimoniates, 
the acid itself being the antimonic. 

Formerly, there were at least forty different preparations 
of antimony, known and used in medicine. At present this 

In -what state does columbium exist combined with iron ? What is the 
specific gravity of columbium ? What is the ore from which antimony is 
obtained ? In what manner is this metal obtained from its ore ? What is 
the color and what the specific gravity of antimony ? In how many propor- 
ions does oxygen combine with antimony ? What are the oxides called? 



METALS. 283 

number is reduced to three or four, and of these only one is 
in general use, viz., the tartrate of antimony and pot as sa^ or 
tartar einetic. 

ANTIMONY AND SULPHUR. 

519. The native sulphuret of antimony, as stated above, 
is the onlj^ ore from which the metal is extracted. This is 
generally found in compact masses, though it sometimes 
occurs in long crystals, interlacing each other. It is of a 
leaden gray color, with a metallic lustre. 

The same compound may be formed by fusing antimony 
and sulphur together, or by transmitting sulphuretted hy- 
drogen through a solution of tartar emetic. 
Sulphuret of antimony is composed of 
Antimony 1 equivalent, 65 
Sulphur 1 equivalent, 16 

URANIUM. 

Equivalent, 217. 

520. This metal was first detected in a mineral found in 
Saxony, which, from its black color, was called pitchblende. 
This ore, now called black oxide of uranium^ contains ura- 
nium in the state of an oxide, mixed with the oxides of iron 
and lead. 

The metal is reduced from its oxide to the metallic state, 
with great difficulty, even in the laboratory of the chemist. 
According to Klaproth, who discovered it, uranium is of a 
dark gray color, with a metallic lustre, and granular tex- 
ture. It is soluble in nitric acid, fuses only at the highest 
temperature, and affords a deep orange color to enamel. Its 
specific gravity is about 8. 

Chemists are acquainted with two oxides of this metal. 
The protoxide is composed of uranium 217, and oxygen 8. 
The combining number of the protoxide is therefore 225. 

The peroxide consists of 1 proportion of uranium 217, and 
2 proportions of oxygen 16; so that the equivalent number 
for the peroxide is 233. 

The protoxide occurs as a natural product, of a dark eme- 
rald green color, and shining lustre. It is often found at- 

What is the composition of sulphuret of antimony ? What is the ore of 
uranium called ? What is the appearance of uranium ? What is its specific 
gravity ? How many oxides of this metal are known ? What is said of tbe 
native protoxide of this metal 1 What use is made of this oxide ? 



284 METALS. 

tached to other minerals, in the lorm of scales, or in bundles 
of crystals, variously grouped, or interlacing each other, 
affording one of the most beautiful products of the mineral 
kingdom. This oxide is also formed by art, and is em- 
ployed to give a black color to porcelain, the change from 
green to black being produced by the heat of the porce- 
lain furnace. 



Equivalent, 48. 

521. The chemists have proved that a metal called cerium 
exists in a reddish brown mineral found in Sweden, and 
called cerite^ or siliceous oxide of cerium ; and also in a min- 
eral found in West Greenland, and called Allanite. 

The properties of this metal are little known, it having 
never been obtained, except in minute quantities, not larger 
than a pin's head. 

It has, however, been ascertained, that cerium combines 
with oxygen in two proportions, and that its combining or 
equivalent number is 48. These oxides are composed of 
cerium 48, and oxygen 8, forming the protoxide, whose 
equivalent, therefore, is 56. The deutoxide contains the 
same quantity of metal, with one and a half proportions of 
oxygen. Its equivalent is, therefore, 60. 

LANTANUM. 

Equivalent unknown. 

522. Lantanum was discovered by Mosander, in 1839, 
mixed with cerium, in an ore found in Sweden. Its name 
is from the Greek, and signifies to lurk^ or elude^ in allusion 
to its remaining unknown so long, its oxide having been 
confounded with that of cerium. One of its oxides is of a 
brick-red color, and its basic powers are said to be very ener- 
getic. Very little is yet known of its properties. 

Mosander has quite recently announced the discovery of 
another new metal found in the ores of cerium, which he 
called Didymium. Of it we know nothing. " 



Equivalent, 30. 

523. The ore from which this metal is extracted, is called 
arsenical cobalt-. It is found in primitive rocks, both dissem- 



METALS. 285 

inaled and in veins, associated with nickel, silver, bismuth, 
arsenic, and copper. 

When this ore of cobalt is heated in contact with the air, 
the arsenic is expelled in the form of arsenious acid, and the 
sulphur, which it also contains, is converted into sulphureous 
acid gas, and escapes. By this process, the ore commonly 
loses more than half its weight, and there remains in the 
furnace an impure oxide of cobalt, called zaffree. 

When zaffree is heated with sand and potash, there is 
formed a glass of a beautiful blue color, which, when pul- 
verized, is extensively known and used under the name of 
smalt. The blue color of porcelain and earthenware, is pro- 
duced entirely by this oxide of cobalt. Paper and hnen, 
also, receive their bluish tinge from this oxide. 

From the oxide of cobalt, or zaffree, the metal may be 
obtained by heating that substance in contact with some 
carbonaceous matter. If it is intended to obtain the metal 
in its pure state, the zaffree must first be purified from the 
iron, or other metals, which it may contain. 

Cobalt is a brittle metal, of a reddish brown color, and 
slightly metallic lustre. It is fused with difficulty. Its spe- 
cific gravity is 8.5. It is attracted by the magnet, and is 
capable of being permanently magnetic. Muriatic or sul- 
phuric acid acts but shghtly on this metal, but it is readily 
soluble in nitric acid. 

Cobalt does not attract oxygen by exposure to the air, but 
by a long continued and strong heat, it is converted into an 
oxide of a deep blue or nearly black color. The atomic 
weight of cobalt has been lately determined. 

This metal is the base of that curious liquid called sym- 
pathetic inkj and which may be prepared in the following 
manner : 

Dissolve one part of cobalt, or zaffree, in four parts of 
nitric acid, and assist the solution by heat. To this solution 
add one part muriate of soda, and four times as much 
water as there was acid. 

524. Characters written on paper, v/ith this ink, are illeg- 

What is said of the existence of the metal cerium ? When and by whom 
was lantanum discovered? What is known of this metal ? What is said of 
the oxide of cerium ? From what ore is the metal cobalt obtained? What 
is zaffree ? What is smalt? What is the use of the oxide of cobalt ? How 
may metallic cobalt be obtained from the oxide ? What is the appearance of 
cobalt? What is the specific gravity of cobalt? What is said of the mag- 
netic property of cobalt ? What acid is the proper solvent of cobalt ? Whal 
is the method of preparing sympathetic ink ? 



286 METALS. 

ible when the paper is cold, but become plain, and of a 
beautiful green color, when the paper is warmed. This ex- 
periment is rendered still more pleasant bj drawing the trunk 
and branches of a tree, in the ordinary manner, and then 
tracing the leaves with the solution of cobalt. In winter 
such a tree wiU appear without leaves, except when wanned, 
but in the summer, particularly if placed in the sun, it will 
be covered with beautiful green foliage. Screens, painted 
with this solution, will show their green when in use, but 
will immediately begin to fade when carried away from the 
fire. 



Equivalent, 28. 

525. Nickel is generally found mineralized by the acids 
of arsenic. The Saxon ores, among which this metal is 
found, are mixtures of lead, copper, iron, cobalt, and arsenic, 
combined with sulphur and oxygen. In nearly every 
instance, where meteoric iron, or other meteoric products 
have been analyzed, they have been found to contain this 
metal. 

Nickel, being of no use in the arts, is never reduced to its 
metallic state, except in the laboratories of chemists, as spe- 
cimens or curiosities. 

Nickel has a strong metallic lustre, and is nearly the color 
of tin and silver. It is both ductile and malleable, and hke 
iron and cobalt, is attracted by the magnet, and may be 
made permanently magnetic. Its specific gravity, after being 
hammered, is 9. It is exceedingly infusible, and suffers no 
change at common temperatures, when exposed to the air; 
but is slowly oxidized at a red heat. The muriatic and sul- 
phuric acids do not act on nickel, but it is readily oxidized 
and dissolved in nitric acid. 

Nickel combines with two proportions of oxygen. The 
protoxide is composed of nickel 28, and oxygen 8. The 
peroxide of nickel 28, and oxygen 16=44. 

BISMUTH. 

Equivalent, 72. 

526. Bismuth occurs native, and in combination with sul- 
phur, oxygen, and arsenic. That which is employed in the 

What are the pec\iliar properties of this ink ? 



METALS. 287 

arts and in commerce, is derived chiefly from the native 
metal. Bismuth has a reddish white color, a brilhant lus- 
tre, and a fohated structure. It fuses at 476°, being, with 
the exception of tin, the most fusible of the solid metals. 
When slowly cooled, this metal may be obtained in octohe- 
dral crystals. Its specific gravity is 10. 

Bismuth enters into the composition of printing type ; and 
its oxides are employed as paints, and in medicine. 

BISMUTH AND OXYGEN. 
OXIDE OF BISMUTH, 80. 

1 eq. Bismuth, 72+1 eq. Oxygen, 8. 

FLOWERS OF BISMUTH. 

527. Bismuth combines with oxygen in only one propor- 
tion, forming a yellowish white oxide. This may readily 
be formed by submitting the metal to a strong heat in the 
open air. It takes fire and burns with a blue flame, while 
the oxide falls down in the forai of powder. 

Bismuth is not readily soluble in the muriatic or sulphuric 
acids, but the nitric acid dissolves it with facility, forming 
nitrate of bismuth. 

When nitrate of bismuth, either in crystals or in solution, 
is thrown into water, a copious precipitate subsides, in the 
form of a beautifully white powder. This is the sulnitrate 
of bismuth, and was formerly known under the name of 
magistery of bismuth. This is employed as a cosmetic pow- 
der for whitening the complexion, but it is a dangerous sub- 
stance for such a purpose, since, if it happens to be exposed 
to sulphuretted hydrogen, it turns black, thus exposing the 
wearer to mortification and detection. 

TITANIUM. 

Equivalent, 24. 

528. Titanium has hardly been seen in its pure metallic 



With what is nickel combined in the natural state ? What is said of the 
existence of nickel in meteoric products ? Is this metal of any use in tlie 
arts ? What is the appearance of nickel ? What is said of its magnetic 
property ? What is its specific gravity ? In what acid does nickel dissolve ? 
What are the states in which bismuth is found ? What is the color of bis- 
muth ? What are the uses of bismuth ? In how many proportions does this 
metal combine with oxygen ? How may this oxide be formed ? What use 
is made of the subnitrate of bismuth ? What is said of the existence of 
titanium '' 



288 METALS. 

State, but the analysis of its oxides proves that such a metal 
exists. 

The ores of this metal are considerably numerous, and 
are widely disseminated. The native oxides of titanium 
sometimes occur in long striated, acicular crystals, of a red 
dish brown color, and shining metaUic lustre. Such crys- 
tals are sometimes contained in transparent pieces of quartz, 
forming specimens of singular beauty. 

The artificial oxides of this metal are white, and are ob- 
tained by difficult processes. They hold their oxygen with 
such tenacity that all attempts to reduce them, by means of 
heat and a combustible, in the usual manner, have failed. 

The equivalent numbers of these acids have not been de- 
termined with certainty. 

TELLURIUM. 

Equivalent, 32. 

529. This is an exceedingly rare metal, being hitherto 
found only in the gold mines of Transylvania, and at Hun- 
tington, in Connecticut. It occurs in the metallic state, as- 
sociated with gold and silver, lead, iron, and sulphur. The 
color of tellurium is between those of zinc and lead ; texture 
laminated, like that of antimony, which it also resembles in 
some of its properties. It melts at about 600° ; has a spe- 
cific gravity of 6. 11 ; is brittle, and easily reduced to pow- 
der. When heated before the blowpipe, it takes fire, burns 
rapidly with a blue flame, and is dissipated in gray fumes, 
which are an oxide of the metal. 

This oxide, which is the only one tellurium forms, is com- 
posed of 32 parts of this metal and 8 parts of oxygen ; so 
that 32 is the atomic weight of tellurium, and 40 the equiva- 
lent of its oxide. 



COPPER. 



Equivalent, 32. 

530. Copper is found native, also combined with sulphur 
with oxygen, with carbonic acid, arsenic acid, sulphuric 
acid, muriatic acid, and with several of the metals. Its 
ores are very numerous, and some of them highly beautiful 
and interesting. 

What is said of the native oxide of titanium ? Where have the ores of tel 
urium been found ? In what state does tellurium occur? What is the coloi 
of tellurium? What is the composition of the oxides of tellurium? What 
are the substances with whioh copper i"^ found combined ? 



METALS. 28S 

The uses of this metal are numerous, and well known. 
In the metallic state, it forms a part of brass, of pinchbecks 
Df Dutch gold, and many other alloys. 

When dissolved in various acids, it forms compounds 
which are employed for a great variety of useful purposes. 

The green pigment, verditer, is a nitrate of copper, pre- 
cipitated by carbonate of lime. Verdigris is an acetate of 
copper. Mineral green is a sulphate of copper, precipitated 
by caustic potash. 

Copper receives a considerable lustre by polishing, but soon 
tarnishes when exposed to the open air. Its specific gravity 
is 8.78, and is increased by hammering. It is malleable 
and ductile, and its tenacity is inferior only to iron. It 
hardens when heated and suddenly cooled. At a red heat, 
with access of air, it absorbs oxygen, and is converted into 
the peroxide, which appears in the form of black scales. 

Nitric acid acts on this metal with vehemence, and it is 
dissolved slowly in the muriatic and sulphuric acids. The 
vegetable acids, as vinegar, also dissolve copper when ex- 
posed to the air, but not otherwise, the oxygen of the atmos- 
phere assisting in the oxidation of the metal. 

COPPER AND OXYGEN. 

PROTOXIDE OF COPPER,, 4 0. 

1 eq. Copper, 32+1 eq. Oxygen, 8. 

RED OXIDE OF COPPER. 

531. The red, or protoxide of copper, is found native in 
the form of regular octohedral crystals, variously truncated, 
and forming specimens of great beauty. It may also be 
prepared artificially, by mixing 64 parts of copper filings 
with 80 parts of the peroxide in powder, and heating the 
mixture to redness in a close vessel. By this process, the 
copper filings attract one proportion of oxygen from the per- 
oxide, which contains twice the quantity of oxygen con- 
tained in the protoxide. Thus the quantity of oxygen is 
equalized, and the whole is converted into the protoxide. 

This experiment affords a very simple illustration of the 
law of definite proportions. Eighty parts of the peroxide of 
copper contains 32 parts of the metal, and 16 of oxygen. 

What are the principal uses of copper ? What is the specific gravity of 
copper? How may copper be converted into a peroxide ? What acids dis 
solve this metal ? In what form does the protoxide of copper occur ? How 
may ihe protoxide of copper be prepared by art ? 

13 



290 METAliS 

Wnen this quantity is heated with 32 parts of copper, 1 pro- 
portion, or 8 parts of oxj'-gen, leaves the peroxide, and unites 
with the copper, thus making, in the whole, 112 parts of 
the protoxide, the copper gaining 8, and the peroxide losing 
8, the number for each becomes 40, the equivalent for the 
protoxide. 

PEROXIDE OF COPPER, 48 

1 eq. Copper, 32+2 eq. Oxygen, 16. 

532. This oxide is said to be found' in the native state. 
By art, it may be formed by keeping thin pieces of copper 
at a red heat exposed to the air, or by heating the nitrate of 
copper to redness. 

This oxide is dark brown, or nearly black. When heated 
alone, it undergoes no change, but if heated in a close ves- 
sel, with charcoal, or other combustible, it parts with the 
whole of its oxygen, and is reduced to the metallic state. It 
combines with most of the acids, and produces salts of a 
green or blue color. 

Copper combines with sulphur, and forms a sulphuret of 
the metal. This compound occurs native, and may be 
formed by heating a mixture of copper filings and sulphur. 
It is composed of 32 parts of the metal and 16 of sulphur. 

LEAD, 104. 

533. In a few instances lead has been found in the native 
state ; but it most commonly occurs combined with sulphur, 
forming the sulphuret, of a bluish gray color, and strong 
metallic lustre. This compound is known under the name 
of galena, and is the ore from which the lead of commerce 
is exclusively obtained. 

The color and common properties of lead are well known. 
Its specific gravity is 1 1. In tenacity, it is inferior to all the 
ductile metals. It fuses at about 600°, and when slowly 
cooled, may be obtained in octohedral crystals. When 
newly cut, it has a brilliant metallic lustre, but is soon tar- 
nished by exposure to the air. 

Lead is not oxidized by moisture without the contact of 

Explain how the process for forming the protoxide of copper illustrates the 
law of definite proportions. How may the peroxide of copper be formed ? 
How may the peroxide of copper be reduced to the metallic state ? What is 
the composition of the sulphuret of copper ? In what state is lead chiefly 
found ? What is the common name for sulphuret of lead ? What is the 
specific gravity of lead ? 



METALS. 291 

air, and hence it may be kept under pure water, for any 
length of time, without change. But if water be placed in 
an open vessel of lead, the metal is slowly oxidized, and a 
white crust is formed, at the points of contact between the 
lead, water, and air, which is a carbonate of the protoxide of 
lead. Hence, as the salts of this metal are poisonous, leaden 
vessels open to the air, should never be employed to contain 
water for cuhnary purposes. 

The sulphuric and muriatic acids act slowly upon this 
metal. Concentrated sulphuric acid produces so httle action 
on it, that the acid is made in chambers Hned with lead. 
Nitric acid is the proper solvent of this metal. The solution, 
when evaporated, deposits whitish opaque crys^tals of ni- 
trate of lead. 

LEAD AND OXYGEN. 

534. There are three oxides of lead, which are thus con- 
stituted : 

Lead. Oxygen. 

Protoxide, 104+ 8 = 112 
Deutoxide, 104+12r=116 
Peroxide, 104+16=^120 

Protoxide of Lead. — This oxide is procured in purity, 
when a solution of the metal in nitric acid is precipitated by 
potash, and the precipitate dried. It is of a yellow color ; is 
insoluble in water, and fuses at a red heat. The same oxide 
is formed by heating lead in the open air, and is known in 
commerce by the name of massicot. When massicot is par- 
tially fused, in contact with the air, it becomes of a reddish 
color, and is known by the name of litharge. This appears 
to be a mixture of the protoxide and deutoxide of lead. Lith- 
arge is mixed with oil used in painting, in order to make 
it dry more rapidly. It is probable that this effect is pro- 
duced by the oxygen, which the litharge imparts to the oil. 

The well known pigment called white lead, is a carbonate 
of the protoxide. This substance is prepared by placing 
rolls of thin sheet lead in pots containing vinegar. The 
vinegar imparts its oxygen to the metal gradually, and 

What is said of the oxidation of lead when kept under water? Under 
what circumstances does water become poisonous, when kept in leaden ves- 
sels ? What is said of the action of different acids on lead ? How many 
oxides of lead are there, and what is the composition of each ? What i* 
massicot ? How is litharge prepared ? What is the use of litharge ? What 
is the composition of white lead ? 



292 METALS. 

probably prepares it for the absorption of carbonic acid from 
the atmosphere. Or possibly the lead may be dissolved 
by the acetic acid, and this acetate in its forming state 
decomposed by the carbonic acid of the atmosphere, in the 
same manner that the chloride of hme is decomposed, and 
changed into a carbonate by exposure to the air. White 
lead was formerly considered a peculiar oxide, but analysis 
shows that it is a compound of the yellow oxide, and car- 
bonic acid. 

535. Deutoxide of Lead. — This is the red lead of com- 
merce, and is extensively used as a pigment, and in the 
manufacture of flint glass. It is formed by heating litharge 
in a furnace so constructed that a current of air constantly 
passes over its surface. In this manner, the litharge, which 
is chiefly a protoxide, is converted into a deutoxide, by ab- 
sorbing another proportion of oxygen from the air. 

When red lead is heated to redness, it gives off pure oxy- 
gen, and is reconverted into the deutoxide. 

536. Peroxide of Lead. — This is formed by the action of 
nitric acid on red lead. The red lead, or deutoxide, is de- 
composed by the acid, and resolved in the protoxide which 
it dissolves, and converts into the peroxide, which being in- 
soluble, falls down in the form of a puce colored powder. 
This oxide is insoluble in any of the acids. When heated 
it gives off large quantities of oxygen gas, and is resolved 
into the protoxide. 

537. Sulphuret of Lead. — This compound occurs very 
abundantly as a natural product, and may be formed by 
fusing a mixture of lead and sulphur. 

The lead of commerce, as above stated, is obtained exclu- 
sively from this ore, which is generally known under the 
name of galena. The metallic lead is easily obtained from 
the sulphuret. The ore being placed in the furnace, is 
gradually heated with small wood, or faggots, to drive off 
the sulphur. Afterwards, charcoal and lime are thrown in, 
and the heat is increased. As some portions of the lead be- 
come oxidated by exposure to the air and heat, the charcoal 
reduces these portions by the absorption of their oxygen, 
and at the same time increases the heat. The lime com- 



How is white lead prepared ? What is the deutoxide of lead ? How is 
red lead prepared, and what is its use ? What proportion of oxygen does the 
deutoxide contain ? How is me peroxide of lead formed ? What are the 
properties of the peroxide of lead ? How is lead reduced from the sulphuret ? 



MPJTALS. 293 

bines with the sulphuric acid, which is formed by the union 
of the sulphur of the metal, the oxygen of the air, and the 
water of the wood, and forms a sulphate of lime. Mean- 
time, the metalHc lead, thus reduced, runs down into the 
lower part of the furnace, where it is drawn off into proper 
vessels. 

All the salts of lead act as poisons, with the exception 
of the sulphate, which Orfila has proved is not deleterious. 
The same author has shown that the acetate, or sugar of 
lead, is decomposed in the stomach by sulphate of magnesia, 
or Epsom salt, and that the inert sulphate is thus formed. 
Hence, Epsom salt, or Glauber's salt, which is a sulphate 
of soda, becomes an antidote to the poisonous effects of 
sugar of lead, when taken soon after it. 

VANADIUM. 

Equivalent, 68. 

538. This new metal was discovered by Professor Sef- 
strom in 1830, mixed with some iron ore from Jaberg, in 
Sweden, Its name is from vanadis, a Scandinavian deity. 

In its properties, vanadium appears to be between chro- 
mium and uranium. It forms with oxygen, two oxides and 
one acid, called the vandaic acid, and combines with several 
other simple non-metalHc elements. The metal, which can 
only be obtained by a complicated process, has a strong 
metallic lustre, like silver, and is so brittle, that it can hardly 
be touched without falling into powder. By combination 
with the proper substances, it forms chlorides, sulphurets, 
and phosphurets. Of its uses, nothing more seems to be 
known, than that it makes an excellent writing ink, in the 
form of vanadiate of ammonia, mixed with infusion of nut 
galls. 

SALTS. 

539. The compound resulting from the union of any acid 
with an alkali, an earth, or a metallic oxide, in definite pro- 
portions, is called a salt. 

The substance which combines with the acid to form the 
salt, is called the base. Thus, lime is the base of carbonate 

What are the uses of charcoal and lime in the reduction of lead? What 
compound of lead is said not to be poisonous ? What antidote is mentioned to 
the poisonous effects of sugar of lead? How does Epsom salt act to neu- 
tralize the poisonous effects of the salts of lead ? When was vanadium dis 
covered ? From whence is its name derived ? What is the appearance of 
this metal ? What are its uses ? What is a salt ? What is the base of a salt ? 



294 SALIS. 

of lime. Any substance capable of combining with an acid 
to form a salt, is called a salifiable base. The salifiable 
bases, therefore, are the alkahes, the earths, and metallic 
oxides. 

Any compound, which is capable of uniting in definite 
proportions with a salifiable base, or which in solution is 
sour to the taste, or reddens vegetable blues, is an acid. 

From this definition, it will be observed that acids are not 
necessarily sour to the taste. This, in many instances, 
arises from their insolubility, for an insoluble acid neither 
tastes sour, nor changes the color of vegetable blues. Other 
acids, which, though soluble, do not taste sour, and have 
little, if any action on colors, still have the property of neu- 
tralizing alkahes, and combining with salifiable bases in 
definite proportions ; such is the prussic acid. 

It was formerly supposed that all the acids contained 
oxygen, as the acidifying principle, but we have already had 
occasion to remark, that there are several known exceptions 
to this truth. Since the discovery of the compound nature 
of the alkalies, and the simple nature of chlorine, it is found 
that some compounds, in which oxygen exists as an element, 
are alkalies, and that others, containing no oxygen, are 
acids. Thus, the metal potassium, combined with oxygen, 
forms the alkah potassa, and chlorine, united to hydrogen, 
forms muriatic acid. 

540. The alkalies are supposed to possess characters 
exactly opposite to those of the acids. Their tastes are 
pungent ; they neutrahze the acids, and change vegetable 
blue colors to green. There are, however, many compounds, 
capable of forming salts, and of neutralizing acids, which 
do not possess the latter characters. Thus magnesia, though 
a powerful neutralizing substance, excites no taste, and pro- 
duces little change on vegetable colors. This want of 
action obviously depends on its insolubility in water. 

Thus, a sahfiable base does not necessarily contain sensi- 
ble alkaline properties, but is any substance which forms a 
definite compound with acids, or which being soluble, has 
the alkaline taste, and changes vegetable blues to green. 
All the metallic oxides are salifiable bases. 

What is a salifiable base ? What is an acid ? Are all acids sour to the 
taste? Do all acids contain oxygen ? Do the alkalies contain oxygen? 
Give an instance where oxygen, combined with a metal, forms an alkali: 
Give an instance in which chlorine and another simple substance united, 
form an acid. Why is magnesia tasteless ? Are the metallic oxides salifiable 
bases? 



SALTS. 295 

541. In speaking of the solution of a metal in an acid, it 
must always be understood, that it is the oxide of the metal 
which is soluble, for no metal combines with an acid in its 
metallic state. The action of the acid is first to oxidate the 
metal ; which it does, either by imparting to it a portion of 
its own oxygen, or by assisting it to obtain this principle 
from the water with which the acid is mixed. When 
copper dissolves in nitric acid, the metal is first oxidated at 
the expense of one proportion of the oxygen which the acid 
contains, and hence the fumes of nitrous gas which escape. 
But when zinc dissolves in dilute sulphuric acid, the metal 
is oxidated by the decomposition of the water, and then 
dissolved by the acid, and hence the escape of hydrogen 
during this process. 

542. It is said that at least 2000 salts are known, but this 
is a small number when compared with those which might 
be formed ; for supposing each acid to be capable of forming 
a different compound with each salifiable base, and each 
base a distinct compound with every known acid, the salts 
would be numberless. 

It may be supposed, from the variety of properties pos- 
sessed by the acids, and the salifiable bases, with which 
they are known to combine, that the resulting compounds 
must present a great variety of different qualities, colors, and 
shapes, and in this we are not disappointed. Some of the 
salts are corrosive poisons, others are perfectly inactive on 
the animal system ; some are used as medicines, others as 
paints, others in coloring, &c. 

It is obvious that in this epitome of the science, only a 
limited number of these compounds can be described. These 
we shall arrange in groups, or classes, each group consist- 
ing of the same acid, united to different salifiable bases. 

543. Most of the salts are capable of being crystahzed, 
that is, of forming dry solid figures of determinate shapes. 
During the act of crystalization, many of them combine 
chemically with a definite portion of water, which, there- 
fore, is called the water of crystalization. 

Some salts contain more than half their weight of water ; 

What change do the metals undergo before they are soluble in the acids ? 
In what manner do the metals become oxides before they are dissolved ? 
When zinc is thrown into diluted sulphuric acid, why does hydrogen escape ? 
What number of salts are said to be known ? On what principles are tho 
salts thrown into gioups ? What is the water of crystalization? Do all the 
■«ltg contain water of crystalization "? 



296 SALTS. 

this is the case with sulphate of soda, or Glauber's salt, which 
consists of 72 parts of the drj sulphate, and 90 parts of water. 

Other salts, as muriate of soda, or common salt, contain 
no water of crjstalization. But these salts sometimes con- 
tain particles of water included mechanically within their 
substance, and hence when heated they decrepitate^ or fly in 
pieces, in consequence of the conversion of this water into 
steam. From this cause, common salt decrepitates violently 
when thrown on the fire. 

Salts containing a large quantity of the water of crystal- 
ization, when heated, undergo the aqueous fusion; that is, 
they dissolve in the water they contain. Anhydrous salts, 
or such as are not chemically united with water, when 
heated undergo the igneous fusion. A salt is said to effio- 
resce^ when its water of crystalization evaporates, and it 
falls into a dry powder. 

544. Most of the salts are soluble in water; and with a 
few exceptions, the solvent power of this fluid is in propor- 
tion to its temperature. One of these exceptions is common 
salt, which is equally soluble in cold or hot water. Some 
of the salts require 500 or 600 times their own weight of 
water for solution. This is the case with carbonate of lime, 
and sulphate of lime. In a few instances, as in the sulphate 
of baryta, the salts are entirely insoluble in water. On the 
contrary, some of these compounds have such an affinity for 
water, as to enter into solution with that which they attract 
from the atmosphere. In these instances the salt is said to 
deliquesce. Muriate of hme is an example. It cannot be 
kept in the sohd state, unless closely excluded from the 
atmosphere. 

All the salts are composed of definite proportions of their 
ingredients, and these ingredients are compounded of defi- 
nite proportions of elementary bodies. Thus, sulphate of 
potash is composed of 40 parts of sulphuric acid, and 48 
parts of potash. The acid is composed of 16 parts, or 1 atom 
of sulphur, and 24 parts, or 3 atoms of oxygen. Potash is 
composed of 40 parts, or 1 atom of potassium, and 8 parts, 
or 1 atom of oxygen. 

Why does common salt decrepitate when heated ? What is meant by aque- 
ous fusion? What is meant by igneous fusion ? When is a salt said to efflo- 
resce? What salt is equally soluble in cold or hot water? What salts require 
a large portion of water for solution ? When is a salt said to deliquesce ? 
What is said of the definite proportions of the ingredients and elements ol 
the salts ? What is the composition of sulphate of potash '^ 



SALTS. 297 

545. Thus the sahs are formed by the union of compound 
substances, and their equivalent numbers are the sums of the 
atomic weights of these substances. Thus, the equivalent 
number for the sulphate of potash is 88, being composed ot 
the equivalents for sulphuric acid 40, and the equivalent for 
potash, 48. How these latter numbers are obtained has just 
been explained ; and indeed the whole of the above, so far 
as regards definite proportions, is only a recapitulation ot 
what has already been stated more in detail, m its proper 
place ; but is repeated here, because the doctrine of propor- 
tions applies especially to the composition of the class oi 
compounds which we are now about to describe. 

Some salts combine with each other and form compounds, 
which were formerly known under the name of triple salts. 

But as, in these instances, only two bases combine with 
one acid, or two acids with one base, this kind of union is 
more properly indicated by the term double than triple ; and 
this change being proposed by Berzelius, is now employed 
by recent writers. 

In describing the salts, we shall follow the method already 
obseiTcd in respect to other compounds, and place the equiv- 
alent numbers at the head of each description. 

SULPHATES. 

546. The sulphates, when heated to redness with char- 
coal, are decomposed and changed into sulphurets. The 
oxygen, both of the oxide and the acid of which the salt is 
composed, unites with the carbon, forming carbonic acid, 
while the sulphur and metal combine to form the new com- 
pound, the sulphuret. 

The sulphates in solution, are readily detected by muriate 
of baryta ; the muriate being decomposed by the sulphuric 
acid, an insoluble sulphate of baryta is formed, which falls 
to the bottom of the vessel in the form of a white powder. 

Several sulphates exist in nature, the most abundant of 
which are those of lime and baryta. The sulphate of lime 
is very abundant in some countries, and is employed as a 
manure, and in the arts, under the name of gypsum^ or 
plaster of Paris. 

How is the equivalent number for sulphate of potash obtained ? Wha 
is meant by a double salt? How are the sulphates changed into sulphurets l 
In what manner does the charcoal and heat change sulphates to sulphurets ? 
How does muriate of barytes show the presence of sulphuric acid ? 

13* 



298 SULPHATES. 



SULPHATE OF POIASSA, 88 

1 eq. S. Acid, 40+1 eq. Potassa, 48. 

VITRIOLATED TARTAR. 

547. This salt is prepared by decomposing the carbonate 
of potash with sulphuric acid. Its crystals are in the fonn 
of six-sided prisms, terminating in six-sided pyramids. Its 
taste is saline and bitter. This salt suffers no change on 
exposure to the air. Its crystals contain no water of crys- 
talization, and when thrown on the fire, decrepitate for the 
reason fonnerly explained. These crystals are soluble in 
16 times their weight of water at 60°, 

The composition and equivalent number of this salt are 
seen above. 

SULPHATE OF SODA, 72. 

1 eq. S. Acid, 40-f 1 eq. Soda, 32. 

GLAUBER'S SALT. 

548. Sulphate of soda sometimes occurs as a native com- 
pound, and may be readily formed by saturating common 
carbonate of soda by dilute sulphuric acid. That sold by 
apothecaries is chiefly prepared from the contents of the 
retort after the distillation of muriatic acid. 

This acid is obtained by distilling a mixture of common 
salt, and sulphuric acid. The latter acid, combining with 
the soda of the muriate, the muriatic acid is evolved and 
sulphate of soda formed. This being purified, forms the 
Glauber's salt of commerce. 

Sulphate of soda crystalizes in four and six-sided prisms. 
These crystals when exposed to the air, part with their 
water of crystahzation, or effloresce, leaving the salt in the 
state of a dry powder. By this process the salt loses about 
half its weight. 

According to the analysis of Berzelius, this salt contains 
72 parts of the neutral sulphate, and 90 parts, or ten atoms 
of water. 

The combining proportions, or equivalents, of the salts, 
refer only to the acids and bases which they contain, and 
not to their water of crystahzation. It is found, however, 

How is sulphate of potash formed 1 What is the composition and equiva- 
lent number of this salt ? What is the composition of sulphate of soda ? 
What is the common name of this salt ? How is Glauber's salt prepared ? 
What proportion of water does sulphate of soda contain ? 



SULPHATES. 299 

that the water of crjstalization is always combined in 
definite proportions, as well as the other ingredients. The 
combining number for water, as already explained, is 9, 
and in the present instance the doctrine of multiple pro- 
portions, by a whole number, is found to be precisely true, 
there being 10 atoms, or proportions, of water in this salt. 

SULPHATE OF BARYTA, 118. 

1 eq. S. Acid, 40+1 eq. Baryta, 78. 

HEAVY SPAR. 

549. The native sulphate of baryta is widely dessemi- 
nated, though not often found in very large quantities at 
any one locality. It occurs both massive and in anhydrous 
crystals, which are generally flattened, or tabular. This 
substance is known under the name of heavt/ spar, having 
a specific gravity of nearly 4|, being the most ponderous 
of earthy minerals. 

It is formed artificially by mixing the earth baryta with 
sulphuric acid. 

It is the most insoluble of all the salts, and bears a strong 
heat without suffering any change. 

This substance is sometimes employed to form the solar 
phosphori, a compound which shines in the dark, after 
having been exposed to the light of the sun. 

It is prepared by first igniting the native sulphate, after 
which it is powdered and sifted. It is then mixed with 
mucilage of gum arable, and formed into cylinders about 
the fourth of an inch in thickness. These being dried in 
the sun, are exposed to the heat of a wind furnace supplied 
with charcoal, for about one hour, and the fire suffered to 
burn out. The cylinders will be found among the ashes, 
retaining their original shapes, and must be preserved in a 
well stopped vial. 

When this substance is exposed for a while to the sun, 
and then carried into the dark, it will emit so much light 
as to show the hour by a watch dial. 

What is said of the definite quantity of the water of crystalization ? What 
is the composition and equivalent number of sulphate of baryta? What is 
the common name of this salt ? Is sulphate of baryta a native, or an artificial 
salt ? How is solar phosphori prepared from sulphate of baryta ? What 
curious property has the solar phosphorus ? 



300 SULPHATES. 

SULPHATE OF LIME, 6b 

1 eq. S. Acid, 40+1 eq. Lime, 28. 

GYPSUM. PLASTER, OF PARIS. 

550. This salt occurs abundantly as a natural production. 
It is composed of 68 parts of the pure sulphate, and 18 
parts or two proportions of water. This salt is found crjs- 
talized in broad foliated plates, and also in compact masses. 
It is ground, and spread on certain kinds of land as a 
manure. In this state it is called ground plaster. The 
compact variety is called alabaster^ and is cut, or turned 
into various ornamental articles, such as candlesticks, 
vases and boxes. Some of these specimens are perfectly 
white, and being translucent, are among the most beauti- 
ful productions of the mineral kingdom. Other varieties 
of this mineral are colored with metallic oxides, and pre- 
sent the appearance of clouds, stripes, or spots of red, blue, 
or brown, interspersed, or alternating with each other. 

Sulphate of lime is largely employed in forming the orna- 
mental, or stucco work, for churches and houses. For 
this purpose it is first heated nearly to redness, or as the 
workmen term it, boiled, in order to expel the water ot 
crystalization, and then ground in a mill. In this state it 
is a fine white powder, which being mixed with water 
and cast into moulds of various figures, forms the orna- 
mental work seen on the walls of churches and rooms. 

After being «iixed with the water, it must be immedi- 
ately poured into the mould, for however thin the paste 
may be, it grows hard, or as the workmen call it, sets, in 
a few minutes, and no addition of water will make it 
thin as before. This is owing to the chemical combina- 
tion which takes place between the anhydrous sulphate and 
the water, and by which the latter is made solid. 

Sulphate of lime is soluble in about 500 parts of cold 
water, and as it exists abundantly in the earth, it is more 
frequently found dissolved in the water of wells and springs, 
than perhaps any other salt. When it exists in considera- 

What is the composition of sulphate of lime ? What quantity of water 
does this salt contain ? What is the common name for sulphate of lime ? 
What are the uses of sulphate of lime ? What is the compact variety of 
this salt called ? How is gypsum prepared to form stucco work. ? What 
chemical change is produced when the anhydrous sulphate is mixed with 
water? What is meant by anhydrous f 



SULPHATES 301 

ble quantity, it gives that quality to the water called hard- 
ness. Such water decomposes soap, by neutralizing its 
alkah, and therefore is not fit for washing. 

SULPHATE OF MAGNESIA, 60 

1 eq. S. Acid, 40+1 eq. Magnesia, 20. 



551. Epsom salt is sometimes obtained by evaporating 
the water of springs which contain it in solution, and some- 
times it is made artificially, by first dissolving magnesian 
limestone in vinegar, which takes up the lime and leaves 
the magnesia. The magnesia is then purified by calcina- 
tion, and afterwards dissolved in dilute sulphuric acid, and 
crystalized by evaporation. 

This salt appears in minute quadrangular shining crys- 
tals. These suffer little change when exposed to the air, 
undergo the watery fusion when heated, and are soluble in 
three fourths of their own weight of boiling water. Its 
use, as a medicine, is well known. 

Sulphate of magnesia is composed of 60 parts of the dry 
sulphate, and 63 parts, or 7 atoms of water. 

SULPHATE OF ALUMINA AND POTASSA, 262. 

3 eq. Sulph. Alumina, 174+1 eq. Sulph. Potassa, 88. 

ALUM. 

552. Alum is a substance so well known, that its exter- 
nal appearance requires no description. Its taste is at once 
astringent and sweetish. It is soluble in about its own 
weight of boiling v/ater. It crystahzes in octohedrons, or 
eight-sided figures, and, by pecuHar management, these 
crystals may be obtained of great size and beauty. It is a 
double salt. 

Sometimes alum is found ready formed in earth or friable 
rocks, and is extracted by collecting such earth into proper 
vessels, and pouring on water, which, passing through, dis- 
solves the salt, and holds it in solution. The water being 
then evaporated, the alum shoots into crystals. 

What effect does sulphate of lime have on the water of wells? What is 
the composition of sulphate of magnesia ? What is the common name of sul 
phate of magnesia? What is the use of this salt? How is sulphate of mag 
nesia prepared ? What is the common name r<f sulphate of alumina and pot 
ash ? What is the composition of alum ? What is the process by which 
alum is obtained ? 



302 SULPHATES. 

When the mineral which furnishes this salt is aluminous 
clay, mixed with sulphur and iron, which is more often the 
case, another method is taken. The mineral being exposed 
to heat, or merely to the action of the air, the sulphur 
attracts oxygen, and is converted into sulphuric acid, which 
then combines with the alumina, and forms a sulphate. If no 
potash be present in the earth, this is added, and the whole 
is treated by lixiviation, (that is, pouring on water until the 
salt is dissolved,) and the liquor afterwards evaporated to 
obtain the alum. 

Alum is used in medicine and in the arts. Its composi- 
tion is stated at the head of this section. Alum is the base 
of a curious composition, called Homherg's pyrophorus^ 
which ignites on exposure to the air. It is prepared in the 
following manner : 

Reduce an ounce or two of alum to powder, and mix it 
with an equal weight of brown sugar. Put the mixture 
into an earthen dish, and keep it stirring over the fire until 
all the moisture is expelled. Then, having pulverized it 
finely, introduce the powder into a common vial, coated 
with a mixture of clay and sand. To the mouth of the 
vial, lute a small glass tube, or the stem of a tobacco pipe, 
in order to allow the moisture and gases to escape. The 
vial, thus prepared, is set in a crucible, surrounded with 
sand, and the whole placed in a coal fire, and gradually 
heated to redness. At first, steam will issue from the tube, 
but afterwards a gas, which, being set on fire, burns with a 
blue flame. 

After the flame goes out, keep up the heat for about fif- 
teen minutes, and then remove the crucible from the fire, 
and immediately stop the orifice of the tube with a piece of 
wet clay. When the vial is cool, pour its contents hastily 
into other vials, which are perfectly dxy^ and then cork 
them so as entirely to exclude the air. 

This compound resembles powdered charcoal in appear- 
ance ; but if a few grains be poured out, and exposed to 
the air, it soon glows with a red heat, and will set paper 
or wood on fire. If poured from the vial, at the distance of 
a few feet from the ground, it forms a shower of fire. 
When introduced into oxygen gas, it spontaneously ex- 
plodes, giving out intense heat and light, and affording a 
very brilliant experiment. 

What is the use of alum T How is Homberg's pyrophorus prepared ? 



SULPHATES. 303 

Small vials of this pjrophorus may be preserved for 
years, and may be made highly convenient, especially for 
itinerant smokers, and to those who are travelling through 
a wilderness. 

The ignition of this substance is caused by its strong 
attraction for the oxygen of the atmosphere. 

SULPHATE OF IRON, 76. 

1 eq. Sulph. Acid, 40+1 eq. Oxide Iron, 36. 

COPPERAS. GREEN VITRIOL. 

562. This well known salt is the sulphate of the pro- 
toxide of iron, and may readily be formed by the action of 
dilute sulphuric acid on metaUic iron. The green vitriol of 
commerce is, however, manufactured directly from the sul- 
phuret of iron, which nature furnishes in abundance. For 
this purpose, the ore, being raised from the earth, is ex- 
posed to the air, and occasionally sprinkled with water. 
By a natural process, the sulphur absorbs oxygen from the 
atmosphere, and is converted into sulphuric acid, which is 
retained by the water. The acid thus formed, combines 
with the iron, forming a sulphate of tTie metal, which ap- 
pears, on the decomposition of the ore in a greenish crust. 
The mass is then lixiviated, or washed by pouring water 
through it, by which the salt is dissolved, and afterwards 
obtained in crystals by evaporating the water. 

Sulphate of iron is of a greenish color, has an astringent 
metallic taste, and is soluble in three fourths of its weight of 
boiling water. According to the analysis of Berzelius, it 
contains 76 parts, or 1 equivalent of the sulphate, and 63 
parts, or 7 atoms of water. 

Large quantities of this salt are employed in the arts, 
chiefly for coloring black, and making ink. 

SULPHATE OF ZINC, 82. 

1 eq. S. Acid, 40+1 eq. Ox. Zinc 42. 

WHITE VITRIOL. 

554. When diluted sulphuric acid is poured on zinc, for 

What singular and curious property does this compound possess ? For 
what useful purpose may this pyrophorus be employed ? What is the com- 
position of sulphate of iron ? What is the common name of sulphate of 
iron? How is green vitriol manufactured on a large scale ? Explain the 
chemical changes by which the sulphuret of iron is converted into copperas. 
What are the uses of sulphate of iron ? Of what is sulphate of zinc composed ? 



304 NITRATES. 

the purpose of obtaining hydrogen, the residue, if allowed lO 
stand, forms small white crystals. This is the sulphate of 
zinc. For the purposes of commerce it is made by roasting 
the native sulphuret of this metal, and then throwing it into 
water. The sulphate is formed by the decomposition of the 
sulphuret, on the same principle as above described for the 
manufacture of green vitriol, and being dissolved by the 
water, is obtained by evaporation. 

Sulphate of zinc has a strongly styptic taste, is soluble 
in about two and a half parts of cold water, and reddens 
vegetable blue colors, though strictly a neutral salt. 

This salt consists of 82 parts of the sulphate, and 7 atoms, 
or 63 parts of water. 

It is employed in medicine, as a tonic and emetic. 

NITRATES. 

The nitrates, when thrown on burning charcoal, defla- 
grate, or produce a vivid combustion of the charcoal. This 
is in consequence of the oxygen gas which they yield when 
heated, which unites with the combustible as it is expelled. 

All the nitrates, without exception, are decomposed at 
high temperatures, or by heat alone. Some of them, as the 
nitrate of potash, or nitre, yield oxygen gas in a state of con- 
siderable purity when heated, and hence are employed for the 
purpose of obtaining oxygen. 

As all the nitrates deflagrate when thrown on burning 
charcoal, this simple test is sufficient to distinguish them 
from other salts. Another test of these salts, is their powei 
of dissolving gold leaf, when mixed with muriatic acid. 

The only native nitrates are those of potash, lime, soda 
and magnesia. 

NITRATE OF POTASH, 102. 

1 eq. N. Acid, 54+1 eq. Potash, 48. 

SALTPETRE, OR NITRE. 

555. This salt may be prepared by saturating the com- 

What is the common name of sulphate of zinc ? How is the sulphate of 
zinc of commerce prepared ? What proportion of water does this salt con- 
tain ? What are the uses of white vitriol ? Why do the nitrates deflagrate 
when thrown on burning charcoal ? What gas do the nitrates yield when 
heated? How may the nitrates be readily distinguished from all other salts? 
What nitrates are found in the native state ? What is the composition of 
nitrate of potash ? 



NITRATES. 305 

mon carbonate of potash with diluted nitric acid, and evap- 
orating the solution until crystals are foiined. 

That used in commerce, and for the manufacture of gun 
powder, is prepared bj throwing into heaps, under cover, the 
remains of decayed vegetable and animal matter, found about 
old buildings. Heaps of such earth, when exposed to the 
air under sheds, gradually generate nitric acid, in consequence 
of the combination of the nitrogen, which is always contained 
in animal remains, with the oxygen of the atmosphere. 
The earth from such situations also contains lime, magne- 
sia, and commonly considerable proportions of potash, from 
the ashes of burned wood. Thus there appears to be formed 
in these nitre beds, the nitrates of lime, potash, and magne- 
sia. After the earth has remained in this situation for sev- 
eral months, being now and then sprinkled with water, it is 
lixiviated, and to the solution of these salts there is added a 
quantity of potash, which decomposes the nitrates of lime 
and magnesia, thus leaving the nitrate of potash in solution. 
The nitre is then crystalized by evaporating the water, 
and afterwards further purified for use. 

In the East Indies, this salt is formed spontaneously in 
the soil, and is found in small crystals on its surface. It is 
therefore obtained with great facility, nothing more being 
necessary than to lixiviate the earth and purify the nitre. 

Nitrate of potassa is a colorless salt, of a cool saline taste, 
which crystalizes in six-sided prisms. It contains no watei 
of crystalization, but its crystals always contain more or less 
water mechanically retained in them. When heated, it un- 
dergoes the igneous fusion, and at a red heat is decomposed, 
first giving out oxygen, and afterwards both oxygen and 
nitrogen, and if the heat be continued, there will remain only 
pure potassa. 

In chemistry, this salt is employed in the manufacture of 
nitric and sulphuric acids, and for the purpose of obtaining 
oxygen gas. In the arts, it is chiefly used in the manufac- 
ture of gunpowder and fire-works. 

556. Gunpowder is composed by weight, of six parts nitre, 
one part sulphur, and one of charcoal. These ingredients 
being first finely powdered separately, are then mixed into 

What is the common name of nitrate of potash ? What is the process of 
preparing the nitre of commerce ? In what country is nitre formed spon 
taneously ? When nitre is heated, what gases are expelled, and what sub- 
stance remains in the fire ? What are the uses of nitre ? What is the 
composition of gunpowder ? 



306 NITRATES. 

the form of a paste, with water, and beaten together with a 
wooden pestle, until they become very intimately incorpo- 
rated. This paste is then granulated, by passing it through 
sieves, and carefully dried in the sun. 

557. Fulminating powder is made by mixing in a mortar 
three parts of nitre finely powdered, two parts of carbonate 
of potash, and one part of sulphur. The whole being 
thoroughly mixed by grinding, forms the powder in question. 

When a quantity of this mixture is placed on a shovel, 
and heated gradually, until the sulphur begins to inflame, 
it explodes, giving a loud and stunning report, and leaving 
the ears hardly in a state to hear any thing more for hours, 
or if the quantity be considerable, even for days. Not more 
Lhan 15 or 20 grains of this powder should be exploded at 
3nce, unless in the open air. 

558. Nitrate of Ammonia. — The mode of preparing this 
salt was described under the article nitrous oxide. This salt 
is composed of one proportion of nitric acid, 54, and one pro- 
portion of ammonia, 17 = 71. It also contains one proportion 
of water =9. 

NITRATE OF SILVER, 164. 

1 eq. Nitric Acid, 54+1 eq. Silver, 110. 

LUNAR CAUSTIC. 

559. When silver is thrown into nitric acid, the metal is 
dissolved, with a copious disengagement of red fumes, 
which consist of the deutoxide of nitrogen, formerly de- 
scribed. 

The solution, if allowed to evaporate, will form large 
regular crystals, in the shape of flat rhombs. These, if the 
metal is unalloyed, are pure nitrate of silver. They contain 
no water of crystalization. They undergo the igneous fusion 
at a very moderate heat, and in this state, being cast into 
small cyUndrical moulds, form the substance so well known, 
and so universally employed in surgery, and for other pur- 
poses, under the name of lunar caustic. 

A solution of this salt in water, being applied to animal 
or vegetable substances, stains them, after exposure to light, 

How is fulminating powder prepared? How is this powder used ? Wher 
silver is thrown into nitric acid, what gas escapes ? What is the composi 
tion of nitrate of silver? What is the common name of nitrate of silver' 
What is lunar caustic ? What effect does a solution of nitrate of silvet 
nave on the skin, or hair ? 



CHLORATES. 307 

of a permanent black color. The skin or hair may be made 
black in this manner, and there is no doubt but persons 
have colored their faces and hands with this substance, as 
preparatory to the commission of the worst of crimes. No 
washing, or any other means, w411 whiten the skin, once 
stained with this solution, until the scarf-skin itself wears 
off, or is removed, which requires several weeks. The so- 
lution itself is perfectly transparent, and in appearance can- 
not be distinguished from pure water. 

560. Indelible Ink is a solution of nitrate of silver in water, 
and is well known as the only substance in use, with which 
cotton and linen may be marked in a permanent manner. 

Nitrate of silver, in solution, is decomposed by a variety 
of substances, having a stronger attraction for oxygen than 
the silver has. By the action of such substances, the silver 
is revived, and appears in its metalHc form. Thus, a stick 
of phosphorus placed in this solution, is soon covered with 
metallic silver ; and if the solution be heated to the tempera- 
ture of boiling water, with a little charcoal in it, the metal 
will be reduced, and may be obtained in the form of crystals. 

The composition of the nitrate of silver is seen at the head 
of this section. 

There are many other nitrates, but none of them are of 
sufficient use, or interest, to require a description in this book. 

CHLORATES. 

561. The chlorates resemble the nitrates in many of their 
characters. These salts were formerly called oxymuriates. 
Most of them are decomposed at a red heat, with the evolu- 
tion of pure oxygen gas, and are converted into metallic 
chlorides. 

The pupil may find some difficulty in pointing out the 
distinction between the chlorates and chlorides. The chlo- 
rates are composed of chlorine united to oxygen, forming 
chloric acid, which acid, being combined with the metallic 
oxides, forms chlorates. The chlorides are composed of un- 
combined chlorine, either united to the metals themselves, 
or their oxides. Thus, chloride of lime is composed of lime, 
or oxide of calcium, and chlorine. But chloride of calcium 



What is indelible ink ? What substances are mentioned, which decompose 
nitrate of silver ? What were the chlorates formerly called ? What is said 
of the decomposition of the chlorates by heat ? What is the difference be 
Iween the chlorates and the chlorides ? What are the chemical changes by 
^hich the chlorates are converted into the chlorides ? 



308 CHLORATES. 

IS composed of the two simple bodies, chlorine and the meta. 
calcmm, consequentlj^ contains no oxygen. 

When the chlorates are decomposed by heat, as abo-ve 
stated, and converted into chlorides, the change is produced 
by the expulsion of the oxygen which the compound con- 
tained, and the subsequent union between the chlorine and 
the base of the alkali, or the metal itself Thus, when chlo- 
rate of potassa is heated, its oxygen escapes, while the 
chlorine remains, and combines with the base of the alkali, 
forming chloride of potassium. 

In producing the chlorates, it is not necessary that the 
chloric acid should first be formed, and then combined with 
the salifiable base, since the same result is produced by 
merely passing the chlorine through a solution of the alkali. 
This will be explained under the chlorate of potassa. 

The chlorates are all of them artificial compounds, none 
of them having been discovered in the native state. Most 
of them yield their oxygen to combustibles with such facility 
as to produce explosion. Thus, when chlorate of potash 
is rubbed in a mortar with phosphorus, or stiiick in contact 
with sulphur, violent detonations are produced. 

CHLORATE OF POTASH. 

I eq. Chloric Acid, 76+1 eq. Potash, 48. 

OXYMURIATE OF POTASH. 

562. The chlorate of potash is formed by passing chlorine 
gas through a solution of the pure caustic alkali in water. 

The pure potash is readily prepared in the following man- 
ner. Make a solution of the carbonate of potash in its own 
weight of hot water, in an iron vessel, and add to this as 
much quicklime by weight as there was potash, and let the 
mixture boil for about ten minutes. Then strain the solu- 
tion through a linen cloth, and it will be fit for use. 

The lime absorbs the carbonic acid from the potash, form- 
ing with it an insoluble compound, thus leaving the alkali 
in its pure, or caustic state. 

The caustic potash being placed in a proper vessel, the 

In producing the chlorates, is the chloric acid first formed, or is it only ne- 
cessary to pass the chlorine through the alkaline solution? Do any of the 
chlorates occur in nature ? What is said of the facility with which the chlo- 
rates yield their oxygen to combustibles ? What is the composition of cklo- 
rate of potash ? How is caustic potash prepared ? 



CHLORATES. 309 

chlorine is passed into it as long as any of the gas is ab- 
sorbed. 

560. Apparatus for Chlorate of Potash. — The apparatus 
for this purpose is represented at Fig. 17. 

The solution is con- 
tained in the three necked p- <^^ 
bottle. The chlorine may Vj ©• • 

be evolved by first intro- J\ | 

ducing into the retort two W | I 

ounces of finely powdered k^ x-^X \%.K 

black oxide of manga- f^ r~~-^^^52^ i P-K 
nese, and after every fafel^ y* j \ \ 

thing is arranged, as in ^^^ ^ — ^ L! 

the figure, pouring on 

this, through the safety tube, four ounces of muriatic acid, 
and then applying a gentle heat. When the solution is 
saturated, the gas will pass oflT by the bent tube into the 
open air. 

To obtain the salt, the solution is evaporated with a 
gentle heat, and on cooling, small shining crystals of chlo- 
rate of potash will be deposited. The first product only 
must be reserved for use, as the solution will afterwards 
form crystals of muriate, instead of chlorate of potash. 

In the production of this salt, by the above process, the 
chloric acid is formed by the decomposition of the water, 
the oxygen of which unites with one portion of the chlorine 
to form the acid, while the hydrogen thus disengaged, 
unites with another portion of the chlorine, forming muriatic 
acid. Hence the solution as above intimated, contains both 
muriate and chlorate of potash. 

V/hen chlorate of potash is heated, it gives off oxygen 
gas nearly pure, and chloride of potassium remains. 

561. Detonates with Sulphur. — If two grains of this salt 
are mixed with one grain of sulphur, and the mixture is 
struck, or pressed suddenly, a loud detonation is produced. 
When struck in contact with powdered charcoal, a similar 
effect results. If a grain of the chlorate and half a grain 
of phosphorus be rubbed together in a mortar, very violent 
detonations will be the effect. In making this experiment, 

What is the use of the lime in preparing caustic potash ? Explain the pro- 
cess by whicn chlorate of potash is formed. How is the chloric acid formed 
|jy this process ? Whence comes the muriate of potash which the solution 
contains? Mention some of the experiments which may be made with this 
salt and a combustible. 



310 PHOSPHATES. 

the hand should be covered with a glove, and the face pro- 
tected by a mask, or averted, as the inflamed phosphorus 
is sometimes projected several feet by the explosion. 

If a little of this salt be mixed with twice its weight of 
white sugar, and on the mixture a few drops of strong sul- 
phuric acid be poured, a sudden and vehement inflammation 
will be produced. 

These phenomena are owing to the facility with which 
the chlorate of potash parts with its oxygen to combustible 
substances. 

562. Friction Matches. — This salt forms the base of the 
matches, by which a light is instantly obtained. The chlo- 
rate being finely pulverized by itself, is then mixed with 
twice its weight of white sugar, moistened so as to prevent 
explosion, and afterwards made into a paste with mucilage 
of gum arabic. A httle of this paste is fixed on the ends 
of brimstone matches, so that when it is inflamed, first the 
sulphur and then the wood is set on fire. These matches 
require only to be rubbed on a rough body when they in- 
stantly burst into flame. 

Attempts are said to have been made in France, on a 
large scale, to substitute the chlorate of potash for nitre in 
the manufacture of gunpowder. But it was found that 
the workmen could not mix the ingredients, under any cir- 
cumstances, without the greatest danger, and that in many 
instances explosions took place after the powder was pre- 
pared ; the attempt was therefore abandoned. Attempts 
have also been made to use mixtures of this salt for per- 
cussion priming, but it was found that the chlorine acted 
so readily on the iron, as soon to injure the gun, and it was 
therefore laid aside, for the fulminating mercury, which is 
now generally used for this purpose. 

PHOSPHATES. 

563. The phosphates of the metals are converted into 
phosphurets by heat and charcoal. Some of the alkaline 
and earthy phosphurets undergo a partial decomposition by 
the same means, while others are not changed. A number 
of phosphates are found in the native state, such as those 
of iron, lime, copper, and lead. 

How are the red matches prepared from this salt ? What is said of the 
attempts made to substitute the chlorate of potash for nitre, in the prepara- 
tion of gunpowder ? What are the phosphates which occur in the native 
state ? 



BORATES. 311 

PHOSPHATE OF SODA, 64. 

1 eq. Acid, 32+1 eq. Soda, 32. 

564. This salt is prepared on a large scale in chemical 
manufactories, by neutralizing, with carbonate of soda, the 
super-phosphate of Hme, procured by the action of sul- 
phuric acid on burned bones. The phosphate of lime, 
which the solution contains, is separated by filtration, and 
the liquid containing the phosphate of soda is then evapo- 
rated until crystals of the salt are deposited. 

The phosphate of soda is composed of one proportion of 
the acid, 32 ; one proportion of soda, 32 ; and twelve pro- 
portions of water, 108. It is employed in medicine, and in 
chemistry, as a re-agent. 

BORATES. 

565. The borates are few in number, and being, most of 
them, of no use, are little known. They are distinguished 
by imparting a green color to the flame of alcohol, when 
dissolved in it. Any borate, being first digested in sul- 
phuric acid, then evaporated to dryness, and the residue 
boiled in alcohol, produces this effect. Hence, this is the 
test for these salts. 

BIBORATE OF SODA, 80. 

2 eq. B. Acid, 48+1 eq. Soda, 32. 

BORAX. 

566. This is the only borate of any consequence, either in 
chemistry, or the arts. It occurs native in certain lakes in 
Persia and Thibet, which are said to be supphed from springs. 
The edges and shallow parts of these lakes are covered with 
a crust of borax, which being removed, another deposition is 
formed. It is imported into Europe and America in its rough 
or impure state, under the name of Tincal, and which being 
purified, forms the refined borax of commerce. 

This salt is capable of being crystalized, in six sided 
prisms, though more commonly seen in amorphous pieces. 
It is soluble in six times its weight of boiling water. 

What is the composition of phosphate of soda ? How is the phosphate of 
soda prepared on a large scale ? What is the use of phosphate of soda ? 
How are the borates distinguished ? What is the composition of the biborate 
of soda ? What is the common name of this salt ? Whrre is borax found ? 



312 FLUATES. 

When exposed to heat, it enters into the watery fusion, and 
at the same time, swells to several times its former bulk. 
When the water of crjstahzation is expelled, is passes 
silently into the igneous fusion, and forms a vitreous transpa- 
rent globule, called glass of horax. Borax is used as a flux, 
by braziers, and mineralogists, and is employed in medicine, 
in cases of sore mouth. 

Besides the constituents of this salt placed at the head of 
this section, borax contains 8 atoms, or 72 parts of water of 
crystalization. 

FLUATES. 

567. The nature of the fluates, owing to the uncertainty 
which exists concerning the base of the fluoric acid, are 
little known. These salts may, however, be readily identi- 
fied by first reducing them to powder, and pouring on sul- 
phuric acid, when, with the aid of a gentle heat, fluoric acid 
will be disengaged, and may be recognised by its property of 
corroding glass. 

SeveTal fluates are found in the native state, and it is from 
these only, or rather from one of them, the fluate of lime, 
that the fluoric acid is obtained. The topaz is a compound 
of fluoric acid, alumine, and silex. Its chemical name is 
jluosilicate of alumina. 

FLUATE OF LIME, 38. 

1. eq. F. Acid, 10+1 eq. Lime, 28. 

DERBYSHIRE SPAR, 

568. This salt is found in its native state, in many parts 
of the world. It is often seen as an article of luxury, cut 
into the form of vases, candlesticks, or boxes, under the name 
of Derhyshire Spar. Its colors are purple, green, red, blue, 
and white, often mixed in the same specimen, and forming 
one of the most beautiful of mineral substances. This sub- 
stance crystalizes in a great variety of forms, the cube being 
the most common. 

Some varieties of this salt phosphoresce, when thrown upon 
hot iron, emitting fight of various colors, as green, red, blue, &c. 



What is glass of borax ? What are the uses of borax ? VNIiat proportion 
3f water does borax contain? How may the fluates be knowTi? From what 
natural substance is the fluoric acid obtained ? What is the chemical name 
of topaz ? What is the composition, and what the combining number, of 
fluate of lime ? What is the common name of fluate of lime ^ 



CARBONATES. 8)3 

When fluate of lime is exposed to the united action of 
sulphuric acid and heat, it is decomposed, the fluoric acid 
being liberated in the form of gas, while a sulphate of lime 
is formed. By this method the fluoric acid is obtained. 

CARBONATES. 

569. Some of the carbonates exist in great abundance in 
the native state. The carbonate of lime forais entire moun- 
tains. These salts may generally be distinguished from all 
others by their effervescence, when exposed to the action of 
the stronger acids. This is owing to the escape of carbonic 
acid during the decomposition of the salt. Thus, when sul- 
phuric acid is poured on carbonate of lime, the lime and 
acid combine, while the carbonic acid, being thus liberated, es- 
capes through the solution, and occasions the effervescence. 

The carbonates, with the exception of those of potash, 
soda, and ammonia, are very sparingly soluble in water. 
The carbonate of lime is entirely insoluble in pure water, 
but is shghtly soluble in water containing carbonic acid. 

Many carbonates of the metals, as well as of the earths, 
are found native. The carbonates of lime, of soda, barytes, 
strontian, magnesia, manganese, of iron, copper, and lead, 
are all native salts. 

CARBONATE OF POTASH, 70. 

1 eq. C. Acid, 22+ 1 eq. Potash, 48. 

POTASH. PEARLASH. 

570. The well known substance pearlash, is the potash of 
commerce deprived of its impurities, and saturated with car- 
bonic acid. The potash of commerce is obtained by lix- 
iviating the ashes of land plants, or common wood, and 
evaporating the solution to dryness. In this state it is of a 
dark reddish color, and when recently prepared, is exceed- 
ingly caustic to the taste and touch. By age its caustic 
})roperty is gradually lost, in consequence of the absorption 
cl" carbonic acid from the atmosphere. Potash is chiefly 
employed in making soft soap and glass. 

How is the fluoric acid obtained? What carbonate forms entire mountains? 
How may the carbonates be distinguished from all other salts ? What occa- 
sions the effervescence when carbonate of lime is acted on by a strong acid? 
What carbonates are found native ? What is the^composition of carbonafie 
of potash? What is the common name of carbonate of potash? How iS 
potash obtained ? What are the uses of potash ? 

14 



314 CARBONATES. 

ITie bicarbonate of potash is prepared by transmitting a 
current of carbonic acid gas through a solution of the car- 
bonate. This salt contains 44 parts of carbonic acid and 48 
parts of potash, making its equivalent 92. It also contains 
9 parts, or one proportion of water of crjstalization. This 
is far milder, both to the touch and taste, than the carbonate. 
At a red heat it parts with one proportion of its acid, and is 
reduced to a carbonate. 

This salt is in common use under the name sal ceratis. It 
is employed for culinary purposes ; in many of the arts, and 
in medicine. 

The bicarbonate of potash may be obtained in regular 
prismatic crystals by evaporating its solution gradually. 

CARBONATE OF SODA, 54. 

1 eq. C. Acid, 22+1 eq. Soda, 32. 

SODA. 

571. The carbonate of soda is prepared by burning plants 
which grow in the sea, and lixiviating their ashes. The 
impure soda of commerce is known under the name of ba- 
rilla, and is obtained by burning certain sea plants expressly 
for the purpose. An inferior kind is called kelp, and is pre- 
pared with less care and from different plants. 

The carbonate of soda of commerce is prepared by dis- 
solving barilla in water, filtering the solution, and then 
evaporating the water. If the evaporation is conducted 
slowly, the salt shoots into regular crystals. By continued 
gentle heat these crystals part with their water, and are 
rendered anhydrous without loss of carbonic acid. This 
salt dissolves in about its own weight of hot water. 

Carbonate of soda is composed of one proportion of the 
acid, 22; one proportion of soda, 32, and 10 proportions, or 
90 parts of water. 

Hard soap is prepared entirely from soda. Bicarbonate 
of soda is made by transmitting carbonic acid through a so- 
lution of the carbonate in water. It may also be prepared 
by placing vessels containing the carbonate in the vats of a 
distillery, or brewery, where the process of fennentation is 
carried on. By either process the carbonate is made to ab- 

How is the bicarbonate of potash prepared ? What is the comraon name 
of bicarbonate of potash ? How is the carbonate of soda prepared ? What 
is the name of the impure soda of commerce ? What is kelp ? What is the 
composition of carbonate of soda ? What kind of soap is made from sodaT 



MURIATES. 315 

sorb an additional proportion of the acid, and is thus con- 
verted into the bicarbonate. 

This salt contains two proportions of the acid, 44 ; one 
proportion of soda, 32, and 9 parts of water. 

The bicarbonate is in general use as a medicine, and 
forms the alkahne portion of soda powders. It also forms 
the basis of that agreeable beverage, soda water. 

MURIATE s. 

572. The muriates may be distinguished by the emission 
of muriatic acid fumes when tested with strong sulphuric 
acid. And also when in solution, by forming a white in- 
soluble chloride, when tested with nitrate of silver. The 
muriates, when in a dry state, are chlorides. 



MURIATE OF AMMONIA, 54. 

1 eq. M. Acid, 37-}- 1 eq. Ammonia, 17. 

SAL AMMONIAC. 

573. Sal ammoniac was formerly imported from the East, 
and particularly from Egypt ; but has for many years been 
manufactured in large quantities, in several parts of Europe. 
Several processes are used at the different manufactories. 
The following is the method employed at a principal manu- 
factory in Paris. 

Two kilns are constructed of brick, in which are placed 
proper vessels for containing the materials employed. Into 
one of these vessels is placed a quantity of common salt, on 
which is poured sulphuric acid, and into the other are thrown 
animal matters, such as horns, bones, parings of hides, &c. 
On the application of heat there is extricated from one ves- 
sel, muriatic acid gas, and from the other, ammonia. These 
gases are conducted by flues into a chamber lined with lead, 
where they combine, and form solid muriate of ammonia, 
which incrusts the roof and sides of the room, and enters 
into solution with a stratum of water on the floor. 

Muriate of ammonia, as seen above, is composed ot muri- 
atic acid and ammonia. Both these constituents exist in 
the state of a gas, but when combined they form the soHd 
compound in question. 

By what process is bicarbonate of soda made ? How does the bicarbonate 
of soda differ from the carbonate of soda ? What are the uses of bicarbonate 
of soda ? What is the composition of muriate of ammonia ? What is the cone 
mon name of muriate of ammonia ? What is the process for making muriate 
of ammonia? 



3J6 



MURUTES. 



Fig. 78. 



The elements of ammonia, (nitrogen and hydrogen,) exist 
in all animal substances, and the muriatic acid is a constitu- 
ent of common salt. In the above process the ammonia is 
extricated by the heat, while the muriatic acid is evolved by 
the decomposition of the common salt, 

574. This method of preparing sal amnionic may be illus- 
trated in the following manner, and affords a very instruc- 
tive and satisfactory experiment. 

Provide two flasks, each furnished 
with a tube, as represented at Fig. 78. 
Into one of these put a handful of com- 
mon salt, and a little sulphuric acid, and 
into the other put equal parts of pow- 
dered quicklime and sal ammoniac ground 
together. Then invert over the ends of 
the tubes a tall bell glass, or a tubulated 
receiver, as seen in the figure, and apply 
a gentle heat to the bottom of each flask. 
The two gases will be disengaged, and 
combining, will form a white cloud with- 
in the receiver, which will gradually con- 
dense and cover its surface with solid sal 
ammoniac. If one of the gases be in- 
troduced into the receiver without the other, it will remain 
transparent and unseen until it meets the other, when a dense 
white cloud will instantly be formed. 

In this experiment the ammonia is set free, in consequence 
of the decomposition of the muriate by the quicklime, which 
combines with its muriatic acid. 

The articles used in smelling bottles, and called volatile 
saltSj hartshorn, d^c, is a carbonate of ammonia. 




C3 



MURIATE OF BARYTES, 115. 

2 eq. Muriatic Acid, 37+1 eq. Barytes, 78. 

575. This salt is formed by saturating muriatic acid with 
carbonate of barytes. For this purpose, either the native oi 
artificial carbonate may be employed. 

Muriate of barytes crystalizes in four sided tables, and 
contains nine parts, or one proportion of water. It is solu- 



How may the process of making the muriate of ammonia be illustrated by 
the apparatus represented at Fig. 78. What is the composition, and what the 
combining proportion, of muriate of barytes ? How is the muriate of barytes 
prepared ? 



HYDROSULPHURETS. 



317 



ble in about two and a half times its weight of water ; and 
is much employed as a re-agent in chemistry. 

HYDROSULPHURETS. 

576. Sulphuretted hydrogen is formed by the action of 
muriatic acid on sulphuret of antimony, or some other mc- 
talHc sulphuret. 

This gas is capable of forming salts with the alkalies, or 
alkaline earths, when passed into their aqueous solutions. 
It thus performs the office of an acid, and the compounds so 
formed are called hydrosulphurets. 

The hydrosulphurets are all of them easily decomposed, 
with the disengagement of sulphuretted hydrogen ; the fetid 
odor of which, seldom leaves the experimenter in any doubt 
concerning the character of the compound. 

HYDROSULPHURET OF POTASH. 

577. The best method of making this salt, or of impreg- 
nating water with any other gas, is by means of the appa- 
ratus represented by Fig. 79. 

The solution of pure pot- 
ash in water, is placed in 
the lower vessel, while the 
materials for extricating the 
sulphuretted hydrogen are 
contained in the retort. The 
influx of the sulphuretted 
hydrogen into the lower 
vessel, drives the fluid into 
the upper one, the juncture 
between the two being made 
close by grinding. Thus, 
the fluid pressing on the 
gas, the absorption of the 
latter is greatly facilitated. 
In this manner soda water 
may be made, the tube in 
the upper vessel being con- 
venient for the introduction of an additional quantity of 
soda, when required, or for a similar purpose when experi- 
menting on other substances. These vessels being made 

What are the hydrosulphurets ? How are the hydrosulphurets fromed ? 
Explain Fig. 79, and describe in what manner the water presses on a gas 
generated in the retort, and forced into the lower vessel. 



Fig, 79. 




318 HVDRAICDS. 

of glass, the change in the height of the fluid, and conse- 
quently its degree of pressure on the gas, are made ob^ 
vious. 

This salt forms large transparent crystals, in the shape of 
six-sided prisms. Its taste is bitter, and it is soluble in 
water and alcohol. 

COMBINATIONS OF HYDROGEN. 

578. There are several combinations of hydrogen with 
various substances, and several names expressive of such 
compounds, some of which are new, and which, therefore, 
we will explain at this place. 

HYDRACIDS. 

The hydracids are combinations of hydrogen with certain 
bases, which compound performs the part of an acid in the 
formation of salts. These acids and their salts are there- 
fore remarkable for the absence of oxygen, and the pre- 
sence of hydrogen. It was formerly supposed that oxygen 
was the universally acidifying principle, and hence its name, 
as already explained. But further investigations have shown 
that salts are formed without the presence of oxygen, 
hydrogen in one sense, being the substitute for oxygen. 
These compounds, therefore, are called salts of the hydra- 
cids^ in order to distinguish them from the salts of the 
oxyacids, which contain oxygen, as the acidifying principle. 

The substances with which hydrogen unites to form 
acids, are chlorine, iodine, bromine, fluorine, selenium, sulphur, 
and cyanogen. These acids, according to the nomencla- 
ture formerly explained, form severally, hydrochloric, hydri- 
odic, hydrobromic, hydrofluoric, hydroselenic, hydro sulphuric, 
and hydrocyanic acids. The hydrocyanic is the prussic 
acid, the hydrochloric, the muriatic, and the hydrosulphuric, 
sulphuretted hydrogen; to the others, there are no old, or 
common names. 

The salts which these acids form with alkaline or metal- 
He bases, are hydrochlorates, hydriodates, hydrobromates, 
hydrofluorates, hydroseleniates, hydrosulphates, and hydro- 
cyanates. These names of course indicate the constituents 
of the several compounds to which they apply. 

Some of these salts are highly important and universally 

What are the hydracids? 



ORGANIC CHEMISTRY. 319 

known, while others are worthy of notice only as chemical 
compounds. We shall here refer only to the former. 

The Hydrochlorate of ammonia is the muriate of am- 
monia, more commonly known under the name of sal am- 
moniac. 

Hydrochlorate of soda is the muriate of soda, or common 
salt. 

The hydrocyanates^ or prussiates, have already been ex- 
plained. 

The hydroferrocyanates are salts which were formerly 
called triple prussiates. They are combinations of hydro- 
gen, iron, and cyanogen, as the name indicates. 

The term hypo is prefixed to a number of acids and salts, 
to denote the first degree of oxygenation. Hypo means 
jw6, or under^ and is employed in cases where bodies are 
capable of combining with more than two proportions of 
oxygen. The nomenclature of the acids of sulphur forms 
an example. These acids are four in number, depending 
on different degrees of oxygenation, and are termed 1 , hypo- 
sulphurow5 acid ; 2, sulphuroM.y acid ; 3, Ayposulphun'c acid ; 
4, sulphunc acid. When these several acids are combined 
with salifiable bases, the names of the salts thus formed 
are hyposulphites, sulphites, hyposulphates, and suphlates. 



PART III. 

ORGANIC CPIEMISTRY. 

Organic chemistry comprehends the chemical history 
of all those different substances or elements, which form 
vegetable and animal bodies. 

In many respects this department of chemistry differs 
very materially from that of the mineral kingdom. The 
analysis of inorganic bodies show, that each substance 
which differs materially from another substance, contains 
some principle peculiar to itself, or that the difference arises 

What does the third part of this volume treat of? What does organic 
chemistry comprehend ? In what respect does organic chemistry diSer from 
mineral chemistry? 



320 ORGANIC CHEMISTRY. 

from the multiplied proportion of some one constituent, 
while the other remains the same. Numerous instances ot 
both these cases will be found, on referring to the composi- 
tion of various substances, and to such compounds as are 
formed bj the union of different, but definite proportions 
of the same elements. Thus, sulphur, united with 0x3^- 
gen, and carbon united to the same element, form two com- 
pounds differing from each other in every respect, with the 
exception that thej both combine with salifiable bases and 
form salts. And mercury, with one proportion of chlorine, 
forms a compound, which may be taken in large doses, and 
is in general use, as a medicine, while with another propor- 
tion of the same element, it becomes one of the most cor- 
rosive poisons known. 

On the contrary, the elements of organized bodies are 
comparatively few in number, and although the different 
products, of which there is a great variety, must be com- 
posed of different proportions of these few elements, yet the 
resulting compounds of the same elements seldom present 
qualities differing widely from each other, like those of the 
mineral kingdom. 

There is another wide difference between organic and 
inorganic chemistry. The latter presents us only with 
compounds formed in consequence of p,ffinity, or the attrac- 
tion of the heterogeneous particles of matter for each other. 
But organic substances are formed by the action of pecu- 
liar organs, each organ being endowed with the power of 
producing different results from similar elements. 

Thus, the several organs of the same tree produce wood, 
bark, flowers, fruit, gum, honey, &c., from the same ele- 
ments : while the organs of secretion, and growth, in 
animals, produce bone, marrow, flesh, bile, fat, hair, nails, 
&c., from the same food. 

In general the chemist finds little difficulty in decompo- 
sing and afterwards imntating the products of the mineral 
kingdom, by again joining the same elements to each other. 

But although he can decompose the products of organic 
action, and find the proportions of their elements, he never 
has been able to recompose or imitate these compounds. 

What is said of the number of elements in organized bodies? What is 
the difference in the mode in which inorganic and organic substances are 
formed? What substances do the different organs of a tree form, from the 
same elements ? What are the different substances mentioned, which the 
several organs of an animal produce from the same food ? What is said of 
the power of the chemists to imitate inorganic and organic «ubstances ? 



VEGETABLE CHEMIST!?/. 321 

Thus, sugar and gum, are found to be composed of hydro- 
gen, oxygen, and carbon, and the exact proportions of these 
elements which they contain, are known ; but no chemist 
has yet found the means of combining these elements, so as 
again to form sugar and gum. 

Organic substances differ also from inorganic, in their ten- 
dency to decomposition. Thus, all animal and vegetable 
bodies, without exception, when exposed to the agencies cf 
air and moisture, undergo spontaneous changes, their ele- 
ments entering into new combinations, and forming new 
compounds to the entire destruction of the old ones. The 
compounds of the mineral kingdom, on the contrary, are 
generally permanent, many of them having probably not 
suffered the least change since their creation. 

The changes which result from the decomposition of ani- 
mal and . vegetable substances, are often exceedingly com- 
plicated, and particularly when this is produced by heat, 
and in a close vessel. A compound, consisting of carbon, 
hydrogen, and oxygen, when thus treated, will produce 
water, carbonic acid, carbonic oxide, and carburetted hy- 
drogen, and if the substance contains nitrogen, in addition to 
these, there will also be formed ammonia, and cyanogen. 

VEGETABLE CHEMISTRY. 

583. Before proceeding to describe particular substances, 
or the means by which the composition of vegetable pro- 
ducts are ascertained, and to show the elements of which 
they are composed, we shall give a short account of the 
process of vegetation, and point out the chemical changes 
which take place during the growth of plants. 

We have already stated, that the elements of which vege- 
tables are composed are few in number, and that the great 
variety which we observe in plants, and their different parts, 
must therefore arise from the different proportions in which 
these few elements unite. 

The constituents of vegetables are carbon^ hydrogen^ and 
?xygen^ to which is occasionally added small proportions of 
nitrogen. The nitrogen, however, occurs only in such plants 

What is the difference between inorganic and organic bodies with respect 
to the tendency to decomposition ? What is said with respect to the compli 
Gated changes which organic bodies undergo, by decomposition ? What are 
the elements, or constituents of which all vegetables are composed? How is 
the great variety under which vegetables appear accounted for, when their 
elements are so few m number 7 
14* 



322 VEGETATION. 

as emu the animal odor during tlieir decomposition, as cab- 
bage, and some of the mushrooms. 

Notwithstanding the great variety which we observe in the 
texture, color, taste, smell, hardness, and other properties of 
different plants, as well as their several parts, such as flowers, 
seeds, and fruits, it is certain that their compositions differ 
only in respect to different proportions of these elements. 

Essential Organs of Plants. — The essential organs of 
plants, are the root^ the stem^ the leaves^ the flowers^ and 
the seeds. The root serves to attach the plant to the soil, 
and is one of its organs of nutriment. 

The stem^ which is usually erect, serves to elevate the 
leaves, the flower, and the fruit, from the ground, by which 
they are exposed to air and light. The leaves are the respi- 
ratory organs of the plant, and the flower perfonns the im- 
portant office of giving rise and nourishment to the seeds^ by 
which the plant is reproduced. 

When a seed is exposed in a situation which favors its 
growth, it soon undergoes a change. It swells, grows soft, 
bursts its membrane, or shell, and at the same time, from 
being insipid and farinaceous, it becomes sweet and mucila- 
ginous, thus becoming fit nourishment for the new plant. 
The stem and leaves are soon after elevated above the earth, 
in search of air, warmth, and light, while the root sinks into 
the ground in search of moisture and nourishment. 

The seed, however various in form, consists essentially of 
the cotyledon^ the 'plumula^ and the radicle. The cotyledon 
contains the matter necessary for the early nourishment of 
the young plant. Sometimes this is single, sometimes 
double, and sometimes it is divided into lobes. The plu- 
mula is enveloped within the cotyledon, and is the part 
which produces the stem and leaves. The radicle shoots 
downwards, and becomes the root. 

The garden bean, hav- Fig. 80. 

ing been a few days in the 
ground, shows all these parts 
in perfection, and is represented 
by Fig. 80. The cotyledons 
form the bulk of the seed, and 
are marked a, a. The plu- d. 
mula, 5, and the radicle, c, are 
represented as beginning to 
shoot, while d^ c?, mark the 
membrane by which the whole has been inclosed 




VEGETATION. 323 

Germination of Seeds. — The circumstances necessary for 
dealthy germination are, a temperature above the freezing 
point, and below 100°; moisture in a certain proportion, de- 
pending on the kind of seed ; and a proper access of air. 

The joint operation of these several agents seem absolutely 
requisite ; for seeds exposed to the action of air and moisture, 
at a temperature below 32°, will not grow, though they may 
not be absolutely destroyed by the frost. Nor will seeds 
vegetate without the contact of some air, though both heat 
and moisture be present. This is shown by burying seeds 
deep in the ground, v/here they are known to lie in a torpid 
state for years, and in some instances, it is supposed, even 
for centuries. Thus, when alluvial soils are exposed to the 
sun, though taken from many feet below the surface, they 
afford grass from the seeds they already contain, and which 
had before remained torpid an unknown length of time, for 
want of the germinating power of oxygen. 

This curious fact is confirmed by the experiment of Mr. 
Ray, who found that seeds exposed to heat and moisture, 
but confined in the exhausted receiver of an air pump, 
showed no signs of germination. 

587. Germination requires Oxygen. — Other experiments 
have proved that seeds will not grow under any circum- 
stances, without the presence of oxygen. Healthy seeds, 
supplied with abundance of heat and moisture, but confined 
to an atmosphere of nitrogen, carbonic acid, or hydrogen, 
showed no signs of germination. 

It appears, however, that only a very small quantity of 
oxygen is required for this purpose, for Mr. Ray found that 
when the receiver of his air pump was not completely ex- 
hausted, the seeds would sprout. In this respect several 
experimenters have been deceived, and in consequence of 
not producing a complete vacuum, have concluded that air 
was not necessary for the process of germination. 

It being thus certain that seeds will not germinate without 
the aid of oxygen, it hardly need to be stated that the 

What are the essential organs of plants ? What purpose do each of these 
organs serve ? When a seed is placed in circumstances favorable to its 
growth, what changes does it undergo? Wliat is said of the stem and roots 1 
Of what does a seed essentially consist ? What is the cotyledon ? What is 
theplumula? What is the radicle ? What are the circumstances necessary 
to healthy germination ? Will seeds grow, when exposed to air and moisture 
under 32° ? How is it shown that seeds will not vegetate without air ? Whai 
was Mr. Ray's experiment on the growth of seeds ? What gas is absolutely 
necessary to the growth of seeds ? 



I 



324 VEGETATIOM. 

fiiture growth of the plant must require the presence of the 
same principle. 

The immediate source from which plants draw their 
nourishment, has been a matter of doubt and controversy. 
It is certain, however, that they will not grow without the 
presence of heat, air, and moisture. It also seems necessary 
for their vigorous growth, that their roots should be placed 
in the earth, but whether this is requisite for their nourish- 
ment, or whether the ground serves merely to give them 
support, was a question long in dispute. 

Van Helmonfs Willow. — Van Helmont planted a wil- 
low, which weighed five pounds, in a pot containing 200 
pounds of earth. This he watered for the space of five 
years, and, at the end of that time, the tree was found to 
weigh 1691 pounds, while the earth in which it had stood, 
being dried as at first, was found to have lost only two 
ounces. Here, then, was an increase of 164 pounds weight, 
and yet the food of the plant had been water only. This 
experiment was supposed to settle all controversy, and to 
decide that the sole food of plants was water. But Mr. 
Boyle afterwards showed, that the water with which the 
tree was moistened, contained earth, from which the willow 
derived at least a part of its nourishment. 

After a great variety of curious, and many elaborate ex- 
periments on this subject, it has been ascertained, that 
plants will germinate in pure water, and that the young 
plant, for a time, will grow with no other aliment ; but that 
it finally grows sickly, and does not come to maturity and 
produce seed, without other nourishment. 

A proof that plants do not thrive on water alone, is drawn 
from the well known fact, that soils become sterile by a long 
succession of crops, but are again made productive by the 
addition of new ingredients. 

Nor does it appear that the simple earths, or clay, without 
some additional ingredients, are sufficient to support the 
growth of vegetables. On making an experiment, by plant- 
ing seeds in pure silica, alumina, or magnesia, moistened 
with pure water, and exposed to proper degrees of heat, it 

What are the agents necessary for the vigorous growth of a plant? What 
was the experiment of Van Helmont, and what was it supposed to decide ? 
How did Mr. Boyle show that the willow did not live on water alone ? What 
has been ascertained with respect to the growth of plants in pure water 1 
What common fact, concerning soils, shaws that plants will not thrive on 
water alone? What is said of the growth of vegetables in the pure earths? 



VEGETATION. 325 

..as found that, although germination was effected, the 
joung plants did not grow, until supplied with water, which 
contained vegetable or animal remains in solution. 

It is for this reason, that earth, taken from a depth below 
the surface, never forms a productive soil. The soils best 
adapted to the growth of plants, always contain a propor- 
tion of vegetable mould, that is, the remains of decayed 
vegetables. This mould contains a quantity of matter 
which is soluble in water, and it is probable that the fer- 
tihty of a soil depends, in a degree, on the quantity of sol- 
uble m-atter it contains, and that in this manner the aliment 
of plants is prepared for absorption by the roots. 

The sap^ which is prepared from the fluid absorbed by the 
roots, is constantly ascending up the vessels of the planfc 
during its growth, until it arrives at the leaves. Here it 
undergoes a considerable change, the watery parts being 
thrown off by the perspiration of the leaves, while that 
which remains is converted into a pecuhar juice, called the 
true sap, which, like the blood of animals, is afterwards 
employed in forming the various substances found in plants. 

The leaves of plants are not only their perspiratory or- 
gans, but they also serve the purpose of respiration, that is, 
they alternately absorb carbonic acid and emit oxygen at 
their surfaces. 

Plants constantly throw off moisture from^their surfaces, 
by perspiration, but the quantity is much larger during the 
day than during the night. Dr. Hales found that a cab- 
bage transmitted, daily, a quantity of water nearly equal 
to half its weight. The office of transpiration is performed 
entirely by the under side of the leaf, and may be almost 
entirely stopped by spreading varnish on that surface. 

Plants absorb Carbonic Acid. — The fact that plants ab- 
sorb carbonic acid was first observed by Dr. Priestley. Hav- 
ing suffered a sprig of mint to vegetate for ten days in a 
quantity of this gas, which would instantly extinguish a 
candle, he found, at the end of that time, that the candle was 
not extinguished by it as before, but that the flame continued 



Why does not the earth, taken from a considerable depth below the sur 
face, form a productive soil ? On what does the fertility of a soil appear to 
depend ? What changes does the sap undergo in the leaves '{ What is the 
true sap, and what its use ? What office do the leaves perform besides tnat 
of perspiration? What proportion of water did Dr. Hales find a cabbage to 
transmit 1 What part of the leaf throws off moisture ? What was Dr 
Priestley's experiment with a sprig of mint and carbonic acid. ? 



326 VEGETATION. 

for a while. Subsequent experiments have shownj tnat 
pure carbonic acid stops the growth of plants, but that a 
small quantity is absolutely necessary to healthful vege- 
tation. 

In Dr. Priestley's experiment, the sprig of mint could not 
have qualified the air in which it was confined, for the sup- 
port of combustion, merely by the absorption of the carbonic 
acid. It must be inferred, therefore, from this experiment, 
that the plant not only absorbed carbonic acid, but that it 
gave out oxygen, or that it converted the carbonic acid into 
oxygen gas, and this inference has been confirmed by ex- 
periment. 

Plants, while growing in the light, absorb carbonic acid 
from the atmosphere, which they decompose ; the oxygen, 
of which this acid is in part composed, being emitted, while 
the carbon is retained by the plant. 

Plants emit Oxygen. — If a growing plant, as a sprig of 
mint, be exposed to the sun, in a glass vessel filled with 
water, it constantly emits from its leaves small bubbles of 
air, which on examination are found to be oxygen gas. Now 
water, under ordinary circumstances, always contains a 
quantity of atmospheric air, and the atmosphere always con- 
tains a proportion of carbonic acid, and hence it may be in- 
ferred, that the water furnishes the air which the plant 
decomposes in^this experiment; that this is the case, is 
proved directly by making the experiment with water, de- 
prived of its air by the air pump, or by boiling, when not a 
particle of oxygen is obtained. 

That it is the carbonic acid which the plant decomposes, 
and from which the oxygen is derived, is proved by two 
facts. The first is, that vegetables are found not to emit 
oxygen, unless carbonic acid be present. The other is, that 
if the plant be confined in a mixture of carbonic acid and 
oxygen, the quantities of which are known, the proportion 
of oxygen will be increased, while that of the acid will be 
diminished. 

From these facts we arrive at the wonderful conclusion, 
that plants absorb carbonic acid from the atmosphere, and 

In Dr. Priestley's e-:periraent, what change did the mint produce on the 
carbonic acid? When a plant is exposed to the sun in a vessel of water, 
wnence comes the carbonic acid which it decomposes ? What two facts 
Drove that plants emit oxygen in consequence of the decomposition of car- 
Donic acid ? Wlien plants decompose carbonic acid, what becomes of the 
carbon ? 



VEfJETATIOJJ. 327 

that they retain the carbon for their own nourishment, but 
return the oxj^gen to purify the air. And from all that is 
known, it is most probable that a great proportion, if not all 
the carbon which wood contains is derived from the atmos- 
phere in this manner. 

Plants absorb Oxygen. — On the contrary, during the 
night, or when the hght of the sun is withdrawn, plants 
absorb oxygen, and forai with it carbonic acid, a part of 
which they emit, and a part is retained. 

It appears from experiment, that vegetables not only cease 
to thrive, but that they actually die, if deprived of this 
nightly inspiration of oxygen. Thus, if a plant be confine 1 
during the day in a portion of carbonic acid, it decomposes 
a part of this gas, which is replaced by the emission of an 
equal volume of oxygen. But at night a part of this oxy- 
gen is absorbed and converted into carbonic acid, which is 
again emitted. Thus, ultimately, the plant decomposes all 
the carbonic acid, because it emits more oxygen during the 
day than it absorbs during the night. But if the oxygen 
which is formed during the day is withdrawn at evening, 
that is, if the plant has a new supply of pure carbonic acid 
every day, it soon droops, and dies for the want of its oxygen. 

The leaves of plants absorb Water. — The leaves of plants 
absorb water, as well as carbonic acid and oxygen. The 
great effect which the dew of night, or sprinkling with 
water, has on a drooping flower- is a proof that the leaves 
imbibe moisture. 

Experiments also prove, that detached leaves often live 
for weeks, when swimming on the water, and that a plant 
which is dying for want of moisture at the root, will revive 
and grow, when a branch with its leaves is placed in a ves- 
sel of water. 

It is most probable, therefore, that during dry seasons, and 
when there is a defect of moisture at the root, that the plant 
is in part sustained by the absorption of water from the air, 
and particularly from the dew as it falls at night. 

Plants incline towards the Light. — In addition to heat 
moisture, oxygen, and carbonic acid, healthy vegetation 
requires a certain quantity of light. It is well known that 

From what source is it probable that plants derive most of their oarbon ? 
When do plants absorb oxygen from the atmosphere ? How is it shown that 
plants droop and die, v/hen deprived of oxygen ? How is it shown that the 
leaves of plants absorb water ? What agent does healthy vegetation require 
in addition to heat, oxygen, water, and carbonic acid ? 



328 V'EGETATIOIS. 

plants which grow in the dark are always nearly colorless, 
and that they appear weak and unhealthy. The disposi- 
tion of plants to enjoy the hght is expressed by their incli- 
nation towards it, when it is stronger in one direction than 
in another. 

Thus, bean, or potatoe vines growing in a dark cellar, 
will always run towards the light, and if possible, will creep 
out into the open air. And flowers, growing in pots placed 
near a window, will always lean towards the light, so that 
to keep them in a vertical position the pots must often be 
turned. In thick forests, the trees grow tall for the same 
reason ; they stretch upwards to enjoy the light and heat of 
the sun. 

Plants which grow in the dark contain more water, and 
less carbon, than those which grow in the sun. A plant 
which grew in the dark, on analysis of one of its branches, 
was found to contain only one ninetieth part of carbon; 
but on allowing the same plant to stand for thirty days in 
the sun, it was found to contain one twenty-fourth part of 
carbon. 

This is readily accounted for, by the fact, that plants grow- 
ing in the dark, emit no oxygen, but give out carbonic acid, 
and hence the defect of carbonaceous matter which they con- 
tain. This also accounts for the circumstance, that when a 
healthy plant is placed in the dark, it not only ceases to form 
carbon, but actually loses a part of that which it before con- 
tained, by the constant emission of carbonic acid. 

ANALYSIS OF VEGETABLES. 

We know, as already stated at page 321, that the chief 
elements of vegetables are carhon^ oxygen^ and hydrogen; 
but that we may take the simplest case to illustrate the 
means of detecting these elements, we will suppose the sub- 
ject of analysis consists only of carbon and hydrogen. In 
this case it is obvious that their entire combustion in oxygen 
gas, would afford nothing but carbonic acid and water. 
Now let us see how we shall come at the proportions of 
these. The quantity of carbonic acid being determined, 
either by weight or measure, the proportion of carbon could 



How do plants show their disposition to enjoy the light ? Why do the trees in 
thick forests grow tall ? What is the difference in composition between plants 
growing in the dark, and in the light? How is the small quantity of carbon 
contained in plants growing in the dark accounted for '' 



VEGETATION. 329 

be inferred; and this ascertained and compared with the 
original weight of the substance to be analysed, would give 
the proportion of hydrogen. Thus, suppose that 7 grains 
of the substance under analysis, yielded by combustion in 
oxj-gen, 22 grains of carbonic acid, then we should know 
that the quantity of carbon present w^as 6 grains, or 1 pro- 
portion of carbon united to two proportions of oxygen, 16 
grains = 22 grains of carbonic acid. The 1 grain of hydro- 
gen of course combined with oxygen to form water, and as 
these unite in the proportions of 1 and 8, there would result 
9 grains of water. 

Suppose, in another instance, the weight of the compound 
to be analysed was 15 grains, and that it was composed of 
hydrogen, oxygen, and carbon, as a piece of wood ; and that 
on subjecting it to heat with oxide of copper, we obtained 
22 grains of carbonic acid, and 9 grains of water, then the 
result would be by inference, that the wood contained car- 
bon 6, hydrogen 1, and oxygen 8 = 15, because, there being 
9 grains of water, we infer by the law of definite proportions, 
hydrogen 1, oxygen 8=9, and there being 22 grains of car- 
bonic acid, this, by the same law, is composed of carbon 6, 
and oxygen 16 = 22. Now, since there was only 15 grains 
of the wood, we infer that 1 proportion of the oxygen was 
derived from the wood, and 1 proportion from the oxide of 
copper. 

The substance to be analysed must first be reduced to 
powder, if capable, if not into small pieces, and mixed with 
about 100 times its weight of oxide of copper, then the mix- 
ture is to be dried in the vacuum of an air pump, wherein 
is also a small vessel of sulphuric acid. The substance for 
analysis is first heated to about 212°, or higher if it will bear 
it, and in this state set under the receiver, before containing 
the acid, and then the air exhausted. The acid by its affin- 
ity to water, abstracts all the moisture still retained by the 
substance in the dish. 

The mixture Fig. 81. 

to be analysed 
being thus pre- 
pared, it is intro- 
duced into the 
tube of green 
glass,a,Fig.81, 
which is open at the large end, and drawn out into a fine 
point at the other, to which is attached the small glass globe 




330 VEGETATION. 

c, communicating with the pipe d, which contains chloride of 
calcium. From the tube d^ there passes a crooked tube, 
leading under the bell-glass /, which stands in the mercury 
bath g. The orifice of the tube «, being closed by a piece 
of clay or otherwise, the tube is heated very gradually by 
burning charcoal, the screen 5, according to the directions of 
Prof Mitscherhch, being necessary "for the purpose of pre- 
venting the heat from spreading too rapidly, lest the glass 
should become fused." 

By means of the heat, the carbon and hydrogen of the 
substance to be analysed, unite with the oxygen given out 
by the oxide of copper, so that a complete combustion goes 
on within the tube, and water and carbonic acid are com- 
posed. The water collects in the globe c, and if any vapor 
passes, it is absorbed by the chloride of potash in the tube d. 
That part of the apparatus being carefully weighed both 
before and after the process, the excess of weight must be 
due to the water. The carbonic acid passes along and 
escapes into the bell-glass f^ within which is the small glass 
globe e, filled with moist caustic potash, into which the car- 
bonic acid is directed, where it is instantly absorbed by the 
potash, and thus the additional weight of the globe and its 
contents will indicate the amount of carbonic acid generated 
during the process. Both the water and acid formed during 
the analysis, can be determined in the manner already 
pointed out, through the aid of definite proportion. If any 
nitrogen is evolved during the process, this will be retained 
under the bell-glass, and its quantity estimated. It will not 
be absorbed by the potash which takes up the carbonic acid. 
Or perhaps where the elements are complicated, one exper- 
iment had better be made for the nitrogen alone. 

RECAPITULATION. 

1. Vegetable substances are chiefly composed of carbon^ 
hydrogen and oxygen^ but sometimes contain portions oJ 
nitrogen. 

2. During the process of germination, the farinaceous sub- 
stance of the seed becomes sweet, and affords nourishment 
to the young plant. 

3. Healthy germination does not proceed without the 
combined presence of heat, water, and oxygen. 

The student should be able to answer all the questions involved in this 
recapitulation. 



VEGE ABLE ACH)S. 331 

4. Seeds will not germinate in a vacuum, or in any gas 
which does not contain oxygen, though heat and moisture 
be present. 

5. Plants receive nourishment from the air, as well as from 
the earth. 

6. Plants nourished by pure water, and having access to 
the air, grow for a time, but do not produce seeds. 

7. The nourishment which plants receive by the roots, is 
probably in a state of solution in water. 

8. The sap undergoes a change in the leaves, where it 
parts with a portion of water, and is thus fitted to form the 
various substances found in vegetables. 

9. In the day time, plants absorb carbonic acid, retain the 
carbon, and emit the oxygen. 

10. In the night they absorb oxygen, and give out car- 
bonic acid. 

1 1. Plants do not live unless they are permitted to absorb 
oxygen during the night ; nor will they live unless they ab- 
sorb a portion of carbonic acid during the day. 

12. Vegetation will continue for some time in either car- 
bonic acid, or oxygen gas ; because when confined in car- 
honic acid^ plants emit a quantity of oxygen during the day^ 
which they absorb at night ; and when confined in oxygen^ 
they give out a quantity of carbonic acid at nighty which 
again serves them during the day. 

13. Healthy vegetation absolutely requires the agency of 
fight. 

1 4. Plants which grow in the dark are white. They show 
their propensity to enjoy the light, by leaning, or creeping 
towards it. 

15. Plants, growing in the dark, do not absorb, and de- 
compose, but emit carbonic acid, and hence they contain a 
deficiency of carbon. 

VEGETABLE ACIDS. 

The vegetable acids are generally less liable to sponta- 
neous decomposition than other vegetable products. They 
form salts when combined with the salifiable bases. Most 
of them are decomposed by hot nitric acid, being converted 
into carbonic acid and water. All of them suffer decompo- 
sition when exposed to a red heat. These acids are nume- 

What is said of the tendency of vegetable acids to decomposition ? Hot?» 
may the vegetable acids be decomposed ? 



332 VEGETABLE ACIDS. 

roii8. but a large proportion of them are of little consequence^ 
and therefore we shall describe only the most useful. 

ACETIC ACID, 50. 

4 eq. Carbon, 24. 3 eq. Oxygen, 24. 2 eq. Hydrogen, 2. 

VINEGAR. 

The acetic acid, or vinegar, exists ready formed m the 
sap of some plants, either in a free state, or combined with 
lime, or potash. It may be formed artificially either by the 
acetous fermentation, or by the destructive distillation of wood. 

In the first case, it is made by exposing wine, cider, beer, 
or any other liquid capable of passing through the acetic 
fermentation, to the action of the air. This last condition 
is absolutely requisite, for no liquid will form vinegar if pre- 
vented from the access of air, that is, from the presence of 
oxygen. The liquid must also be exposed to certain de- 
grees of temperature, for the acetic fermentation does not 
proceed when the thermometer is at 32°, and but very 
slowly when it is near this point. 

In this process, little or no gas is evolved, but on the con- 
trary the oxygen of the atmosphere is absorbed, so that the 
liquid undergoes a slow oxidation. 

The vinegar obtained by the distillation of wood is called 
pyroligneous acid, that is, the acid of burned wood. When 
first made, it is very impure, and of a dark color, holding in 
solution carbon, soot, tar, and volatile oil, which gives it a 
strong smell of smoke. It is purified by a second distilla- 
tion, and is largely employed for manufacturing purposes, 
and particularly in the preparation of white lead. 

The acetic acid is distinguished from all other acids by 
its peculiar flavor, odor, and volatility. Its salts are called 
acetates. These salts are all of them decomposed at a red 
heat, or by the action of sulphuric acid. 

ACETATE OF LEAD, 172. 

1 eq. A. Acid, 504-1 eq. Oxide Lead, 112. 

SUGAR OF LEAD. 

This salt is prepared by dissolving either litharge, or white 
lead, in distilled vinegar. The solution is sweet to the taste, 

What is tL« composition of acetic acid ? Whiat is rhe common name of 
acetic acid ? is vinegar ever found ready formed in plants ? How may this 
acid be formed by art? What liquids form this acid by fermentation '( What, 
conditions are necessary t'^ the production of vinegar by fermentation ? 



VEGETABLE ACIDS. 333 

and hence its common name. It occurs in small shining 
crystals, which contain 27 parts, or 3 atoms of water. This 
salt is partially decomposed when abandoned to the action 
of the atmosphere. It parts with its water of crystahzation, 
and absorbs carbonic acid from the atmosphere, thus being 
changed into a carbonate, or into white lead. We have 
stated in another place, that in the manufacture of white 
lead, the same change is effected ; the lead being first dis- 
solved by the acetic acid, and afterwards changed into a 
carbonate by the action of the atmosphere. 

The acetate of lead is largely employed in the process of 
coloring, and as a sedative and astringent in surgery. 

ACETATE OF COPPER, 130. 

1 eq. Acetic Acid, 50+1 eq. Oxide of Copper, 80. 

VERDIGRIS. 

This salt may be prepared by exposing metallic copper to 
the vapor of vinegar. The process appears to consist in the 
absorption of oxygen from the atmosphere by the metal, after 
which it is dissolved in the acetic acid. 

Verdigris is manufactured largely in the south of France, 
by placing plates of copper between the refuse of grapes 
after the juice is pressed out, for the making of wine. The 
fluids which the grapes still contain, pass through the acetic 
fermentation, by exposure to the atmosphere, and after 
several weeks, the plates acquire a coat of the acetate, 
which being scraped off, they are again exposed to the same 
process. The acetate is afterwards purified by solution, 
and crystahzation. 

OXALIC ACID, 36. 

2 eq. Carbon, 12 + 3 eq. Oxygen. 24. 

ACID OF SORREL. 

The oxalic acid exists ready formed in several plants, 
and particularly in the oxalis acetosella^ or wood sorrel^ and 
also in common sorrel. It is readily prepared artificially, by 

What gas is absorbed from the air by the forming vinegar? What is the 
finegar from distilled wood called ? How is the acetic acid distinguished 
from all other acids ? What is the composition of acetate of lead ? What is 
^he common name for acetate of lead? How is this salt prepared? In what 
manner is this salt decomposed when exposed to the air, and what new salt 
is formed? What are the uses of acetate of lead ? What is the composition 
of acetate of copper ? What is the (^mmon name of this salt ? By what 
chemical process is this salt formed ? How is verdigris made in the large 
way ? What is the oxalic acid composed of? 



334 VEGETABLE ACIDS. 

digesting white sugar in five or six times its weight of nitric 
acid, and evaporating the solution to the consistence of 
sjrup. On coohng, crystals of oxaHc acid will be deposited; 
but they should be purified by solution in water, and again 
crystalized by evaporation. 

Oxahc acid crystalizes in slender, flat prisms, which have 
an exceedingly sour taste, and which in solution combine 
with the salifiable bases, and form a class of salts called 
oxalates. These crystals contain half their weight of water 
of crystalization. 

This acid is easily distinguished from all others, by the 
form of its crystals, and by its solution giving, with lime 
water, a white precipitate, which is not dissolved by adding 
in excess the same acid. Oxalic acid is one of the most 
prompt and fatal poisons known, when taken in large doses. 
Fatal accidents have many times happened, in consequence 
of mistaking this acid for Epsom salts. 

This acid is employed by calico printers, for the purpose 
of discharging certain colors. It is also used in famiHes, 
for taking out spots of iron mould, and other stains. 

The oxalates are none of them of much importance. The 
oxalates of potash, like the acid itself, is sold under the name 
of essential salt of lemons.^ for removing stains from linen. 

TARTARIC ACID. 

4 eq. Carbon, 24 + 5 eq. Oxygen, 40+2 eq. Hydrogen, 2. 

TARTARIC ACID, 66. 

Cream of tartar is the purified lees^ or deposits of wine 
casks. From cream of tartar the tartaric acid is produced, 
by mixing the former with chalk in fine powder, and throw- 
ing the mixture into boiling water, by which the cream of 
tartar, which is a tartrate of potash, is decomposed, and a 
tartrate of Hme is formed. The tartrate of hme is then 
washed, and decomposed by dilute sulphuric acid, which, 
combining with the hme, sets the tartaric acid at hbertj^, 
where it remains in solution. This solution being evapo- 
rated, the tartaric acid is obtained in white crystals. 

This acid is employed by cahco printers, to discharge 

In what plants is this acid ready formed? How is this acid formed by art ? 
What are the salts called, which the salifiable bases form_ with oxalic acid? 
How is this acid distinguished from others ? What is said of its poisonous 
effects? What are the uses of oxalic«cid ? What is the tartaric acid com- 
posed of? What is the substance from which tartaric acid is obtained? By 
what process is this acid obtained ? 



VEGETABLE ACIDS 335 

false prints, and by tallow chandlers to whiten their goods. 
It is also used, when dissolved in a large quantity of water, 
as a cooling beverage in the hot season. When mixed with 
carbonate of soda in solution, it forms the effervescing 
draught called soda powder, of which large quantities are 
prepared and sold during the summer season. 

The effervescence, the only property which makes this 
drink agreeable, is occasioned by the union of the tartaric 
acid with the soda, in consequence of which the carbonic 
acid is liberated, and in escaping through the water, causes 
the effervescence. 

This acid is remarkable for its power of combining with 
two bases at the same time, and forming double salts. The 
most important of these salts is well known under the name 
of tartar emetic. 

TARTRATE OF ANTIMONY AND POTASH, 354. 

2 eq. Tartaric Acid, 132+2 eq. Protoxide of Antimony, 156. 
1 eq. Potash, 48+2 eq. Water, 18. 

TARTAR EMETIC. 

This compound, so singular from the number of constitu- 
ents it contains, is made by boihng the oxide of antimony 
called crocus metallorum, with tartrate of potash, or cream 
of tartar. 

This salt crystaUzes in transparent prisms, which after- 
wards grow white and opaque by exposure to the air. It 
is soluble in about fifteen parts of cold, and three parts of 
hot water. 

When dissolved in water, the solution gradually under- 
goes spontaneous decomposition, and becomes inert as a 
medicine. This may be prevented by the addition of about 
one third part alcohol to the aqueous solution. This salt is 
also decomposed by many re-agents, as by all the stronger 
acids, and several of the alkalies and alkaline earths, and 
even by vegetable substances. Infusion of nutgalls causes 
with it a whitish precipitate, which is considered a com- 
pound of tannin and oxide of antimony. This compound 
is inert, and hence the decoction of chincona bark, as it 

What are the uses of tartaric acid ? What occasions the effervescence of 
soda powders ? ""vVliat is the chemical name of tartar emetic ? What is the 
composition of tartar emetic? How s tartar emetic prepared? What is 
may of the decomposition of the aqueous solution of tartar emetic ? How 
said this decomposition be prevented "^ 



336 ANALYSIS OF PLANTS. 

contains tannin, has been given as an antidote to an over 
dose of tartar emetic. 

CITRIC ACID, 58. 

4 eq. Carbon, 24 + 4 eq. Oxygen, 32 + 2 eq. Hydrogen, 2. 

SALT OF LEMONS. 

This acid is obtained from the juice of l-emons, by the 
same process as that described for tartaric acid. Finely 
powdered chalk is added to the juice, as long as any effer 
vescence ensues. The citrate of lime thus formed, is insol- 
uble in water, and sinks to the bottom of the vessel. This 
being washed, is digested in dilute sulphuric acid, by which 
an insoluble sulphate of lime is formed, while the citric acid, 
being thus set at liberty, remains in the solution, and on 
evaporation is obtained in crystals. 

These crystals are large, transparent, and beautiful. They 
undergo no change by exposure to the air, are exceedingly 
sour to the taste, but when dissolved in a large proportion 
of water, make an agreeable drink, in consequence of retain- 
ing the flavor of the lemon. 

This acid forms salts with the salifiable bases, but none 
of them are of importance. There is a variety of other 
vegetable acids, most of which are of no importance in any 
respect. Some of them have been analyzed, while the 
composition of others are unknown. We may, however, 
conclude, by analogy, that they are all composed of oxy- 
gen, carbon, and hydrogen, in different proportions. 

INGP^EDIENTS OP PLANTS. 

The ingredients of plants are distinct substances, formed 
by their secreting organs, and separable from each other 
without destructive distillation. They are separated by 
certain solvents, which have the power of dissolving some, 
but not others. Thus, water dissolves the gum but not the 
resin, while alcohol takes up the resin and leaves the gum. 
The solvents employed for these purposes are hot and cold 
water, ether, alcohol, and some of the acids. 

Explain the principle on which chincona, or Peruvian bark, has been given 
as an antidote to tartar emetic. What is citric acid composed of? What is 
the common name of this acid? How is citric acid obtained ? What is tha 
use of citric acid ? What are the ingredients of plants ? How are the in 
gredients of plants separated from each other ? What are the principal in 
gradients, or proximate principles of plants ? In what liquid is gum soluble 
Into what substances is gum resolved by sulphuric acid? 



SUGAR. 837 

I'he following are the principal ingredients, or what are 
Cfiiied the proximate principles of plants ; viz. 
Gum, Fixed oil. 

Sugar, Volatile oil. 

Starch, Camphor, 

Gluten, Resins, 

Extractive, Narcotine, 

Lignum, Bitumen, 

Tannin, Vegetable alkalies, 

Coloring mat'.cr, and 

Wax, Vegetable acids. 

We shall examine the properties of only the most im- 
portant of these principles. 



Gum arable may be taken as an example of pure gum. 
It dissolves in water, with which it fu 'ms a viscid solution, 
ox mucilage, from which it may be obta ned in its original 
state, by spontaneous evaporation. It is insoluble in alco- 
hol, or ether, the former precipitating it from the watery 
solution in the form of white flakes. Gum is decomposed 
by sulphuric, and nitric acids. By the former, it is resolved 
into water, acetous acid, and charcoal; the latter produces 
with it oxalic and malic acid. When gum is submitted to 
destructive distillation, it aifords water, carbonic acid, car- 
buretted hydrogen, empyreumatic oil, and acetic acid. 



Sugar is chiefly obtained from the sugar cane^ a plant 
which grows in hot climates, and which yields it in a larger 
proportion than any other substance. It is also procured 
from the sugar maple, by boiling down the sap which flows 
from incisions made in the tree; and from several roots, 
particularly the beet, from which large quantities are made 
in France. 

In the manufacture of sugar from the cane, the first pro- 
cess consists in obtaining the juice, which is done by grind- 
ing and pressure. This is then evaporated by a gentle heat, 
during which a quantity of lime is added, partly for the 
purpose of neutralizing any free acid, and partly for the 

What are the products of gum, when submitted to destructive disti'llation ? 
What are the principal vegetables from which sugar is obtained ? What ia 
the process by which sugar is extracted from sugar cane ? Why is lime 
added to the juice of the cane when boiling ' 
15 



338 STARCH. 

purpose of separating extractive matter, which unites witk 
the hme, and forms a scum on the surface of the HquiA 
Tile evaporation is continued until it acquires the consis- 
tency of sjrup, when it is transferred into wooden coolers, 
where a portion concretes into a crjstalhne mass, and in 
this state forms what is called muscovado or raw sugar. It 
is then placed in vessels with apertures in the bottom, where 
the more fluid parts drain off, and form the well known 
sweet syrup, molasses. 

Refined sugar. — Raw sugar is refined by the following 
process : The sugar being dissolved in water, is mixed with 
the whites of eggs, or the serum of blood, and boiled. The 
albumen or serum is thus coagulated by the heat, and rising 
to the surface, brings with it such impurities as the sugar 
contained, which are removed by a skimmer. When the 
syrup is judged to be sufficiently clear, it is placed in smaller 
pans, and farther concentrated by boiling, and then trans- 
ferred into coolers, where it is agitated with wooden oars, 
until it appears thick and granulated. It now becomes 
white, and the crystals being broken by the agitation, fa- 
cilitates the draining ofif of the colored matter which re- 
mains. 

It is next placed in conical cups of earthenware, of the 
well known form called sugar loaf. These having apertures 
at the bottom, a portion of molasses drains off, leaving 
the sugar much whiter than before. Lastly, a quantity of 
pipe clay is mixed with water to the consistency of cream, 
and poured on the loaves to the thickness of an inch. The 
water from this slowly percolates through the loaves, and 
washes all remains of the coloring matter from the sugar. 
The loaves are then dried by heat, and put in papers for sale. 

Refined sugar undergoes no change when exposed to the 
air, the dampness of raw sugar being caused by impurities. 

Sugar is decomposed by the sulphuric and nitric acids. 
By analysis it is resolved into the usual constituents of vege- 
tables, oxygen, carbon, and hydrogen. 



Starch is an abundant principle in the vegetable kingdom, 
being one of the chief ingredients in most sorts of grain, and 

What is muscovado sugar? How is molasses obtained? How is raw 
sugar refined ? What is the use of the albumen and serum used in this 
process ? How is the sugar purified and whitened after it is placed in the 
conical cups ? 



GLUTJ'^N. 339 

in many roots and seeds. The process for obtaining starcn 
consists in diffsuing the powdered grain or rasped root in 
pnre cold water, bj which the water is rendered white and 
turbid. After some hours, the grosser parts, which in wheat 
consists chiefly of ghiten, are separated by straining, and 
tlie water which passes through, being placed in shallow 
vessels, deposits the starch, on standing. It is afterwards 
washed and dried with a gentle heat. 

If starch be boiled for a considerable time in water con- 
taining about a twelfth of its weight of sulphuric acid, it 
is converted into sugar. By careful analysis, it has been 
found that the only difference between the composition of 
starch and sugar, is, that the starch contains less hydrogen 
and oxygen, in proportion to the carbon, than sugar. How 
the acid acts to convert the starch into sugar, has not been 
satisfactorily explained. During the germination of seeds, 
a similar change is effected, the starch being in part con- 
verted into sugar. 

The principal varieties of starch, are arrow-root, potatoe 
starch, sago, tapioca, cassava, salop, and the starch of 
wheat. 



Gluten may be obtained from wheat flour, by forming it 
into a paste, with cold water, and continuing to wash this 
paste under a stream of the same fluid, as long as any thing 
is carried away. The starch being thus removed, a tough 
elastic substance, of a gray color, will remain, which is 
gluten. 

This substance has no taste, and is insoluble in water, 
alcohol, or ether, but is soluble in alkalies and acids. If 
left to undergo the putrefactive fermentation, it emits an 
offensive odor, similar to animal substances, and from this 
circumstance it is apparent that it contains nitrogen, which 
indeed is proved by its yielding ammonia at a red heat. 

Of all substances, wheat contains the greatest proportion 
of gluten, and it is owing to this circumstance, that wheat 
flour is more nourishing than that of other grain, gluten 
being the most nutritive of all vegetable substances. It is 



What is said of the abundance of starch in the vegetable kingdom ? What 
is the process for obtaining starch ? How raay starch be converted into 
sugar? What is the difference between the composition of starch and sugar? 
What are the principal varieties of starch ? How may gluten be obtained? 
What is the appearance of gluten ? What are some of the properties of 
gluten? Why is wheat flour said to be more nourishing than that of othef 
grain ? 



340 COLORLN'G MATTER. 

also owing to the presence of this substance in the flour, 
that the dough is tenacious, and the bread spongy, or hght, 
the carbonic acid formed during the fermentation of the 
dough, being detained hy the gluten, in consequence of 
which the whole mass is distended with bubbles of air. 

Wheat contains from 18 to 24 per cent, of gluten, the 
remainder being principally starch. 

EXTRACTIVE MATTER. 

Most vegetables, when Lifused for a time in hot water, 
impart to it a brown color. When such solutions are 
evaporated, there remains a solid substance, of a brownish, 
or sometimes of a yellowish color, which is extractive 
matter. 

Extracts are prepared by apothecaries, as a means of 
concentrating the \drtues of plants for medicinal purposes. 
These extracts not only contain the proper extractive mat- 
ter, but several foreign substances also, such as resin, col- 
oring matter, oil, &c. 

COLORING MATTER. 

The coloring matter of vegetables is chiefly red, blue, 
green, yellow, or mixtures of these colors. Nearl}^ all vege- 
table colors are discharged by the continued action of light, 
and without exception, they are all destroyed by the action 
of chlorine. 

Acids and alkalies either destroy, or change the tints of 
vegetable colors. 

The extraction of the coloring principles, and the trans- 
fer of them to different substances, constitutes the art of 
dyeing, an art which, in the succession of ages, has been 
carried to a high degree of perfection. This art has been 
practised from the remotest antiquity ; for the history of 
man informs us, that from the king on the throne, to the 
savage in the ^vildemess, all have ever been fond of deco- 
rating themselves in a variety of colors. 

Colors have been di\dded into suhstantive and adjective. 
Substantive colors are such as do not require the interven- 

In what manner does the gluten in the dough produce the sponginess of 
the bread ? ^^^lat is extractive matter ? What are the principal tints of the 
coloring matter of \ egetables ? What eflfect does light h^ve on the coloring 
principle of vegetables ? "^Tiat are the effects of chlorine on these colors ? 
What constitutes the art of dyeing ? How are colors divided ? What are 
substantive colors ? 



TANNIN. 341 

tion of any other substance to fix them permanently, their 
attraction "^for the cloth being sufficient for this purpose. 
Adjective colors require the intervention of some substance, 
which has an affinity both for the coloring matter, and the 
stuff to be dyed. This intervening substance is called a 
mordaiit. The mordant generally consists of a metallic 
salt dissolved in water, with which the cloth is impreg- 
nated, after which it is passed through the solution of col- 
oring matter. The mordants most commonly employed 
are, muriate of tin, sulphate of iron, acetate of iron, and 
sulphate of alumine. 

Different mordants are used for different colors, and dif- 
ferent kinds of cloth. Thus, black is made with sulphate 
of iron, nutgalls, and logwood. Yellow, with alum, fustic, 
and saffron ; red, of cochineal, madder, red wood, or archil^ ^ 
with muriate of tin, or sulphate of alumine for a mordant * 
Blue is made with indigo, &c. 

TANNIN. 

Tannin is the substance, by the absorption of which the 
skins of animals are converted into leather. The substance 
is contained abundantly in nutgalls, in the bark of many 
trees, particularly the oak, hemlock, and birch, and in most 
vegetable substances which are astringent to the taste. 

Tannin may be obtained from any of these substances, 
by first bruising the article, and then digesting it in a small 
quantity of cold water, and afterwards evaporating the 
water. This substance is of a yellowish brown color, ex- 
tremely astringent to the taste, and soluble in water and 
diluted alcohol. 

Tannin is distinguished by its affording an insoluble pre- 
cipitate with isinglass, or any other animal jelly. It is on 
this principle that the art of tanning leather is founded. The 
hides are laid in vats, and between them there is thrown a 
layer of oak, or other bark, which contains tannin, in coarse 
powder. The tannin of the bark is first dissolved by the 
water, and afterwards combines with the leather, by which 
it is rendered hard, and nearly impervious to water. 

What are adjective colors ? "What are mordants in coloring? What are 
the principal substances used as mordants? What is tannin? What 
are the principal substances which contain tannin ? How may tannin b*» 
obtained ? How is tannin distinguished ? On what principle is the taniuuf. 
of leather founded^ 



342 VEGETABLE OILS. 



VEGETABLE OILS. 



The vegetable oils are of two kinds, Fixed and Volatile. 

Fixed Oils. — These are found only in the seeds of plants, 
and chiefly in such as have two cotyledons, such as almondsj 
linseed, walnuts, and rapeseed. The oil of olives, however, 
is extracted from the pulp which surrounds the kernel. 

The fixed oils are obtained by crushing or bruising the 
seed, and subsequent pressure. They are viscid, nearly in- 
sipid, and inodorous, and generally congeal at a tempera- 
ture considerably higher than 32°. 

The fixed oils, with a few exceptions, undergo little other 
change, by exposure to the air, than those of growing more 
viscid, and acquiring a degree of rancidity. The latter 
change is owing to the absorption of oxygen, for rancid oils 
redden vegetable blues, showing that they contain a quan- 
tity of free acid. 

The absoi'ption of oxygen, by some of the fixed oils, and 
particularly by those of hnseed and rapeseed, is sometimes 
so abundant and rapid, as to set fire to light porous substan- 
ces on which they are spread. 

These are called cases of spontaneous combustion^ and in 
many instances, where these oils have been suffered, either 
by accident or otherwise, to come in contact with cotton wool 
or cotton cloth, destructive fires have been the consequence. 

The alkalies combine with the fixed oils, and form soap. 
The composition of all these oils is, carbon, hydrogen, and 
oxygen. 

Volatile Oils. — Plants and flowers owe their odor and 
flavor to volatile or essential oils. These oils are obtained 
by distilling the plants which contain them with water. The 
water prevents the plants from being burned. Both pass 
into the receiver from the still, where the oil is found either 
at the bottom, or on the surface, as its density is greater or 
less than that of water. Some fruits, however, yield essen- 
tial oil by pressure; such are the orange, the lemon, and 
the bergamot, which contain it in vesicles in the rind of the 
fruit. 

The odor of the essential oils is aromatic, and their taste 
penetrating. They consist of the odoriferous principle, by 

What are the two kinds of vegetable oils ? In what part of plants are the 
fixed oils found ? How are the fixed oils obtained ? What changes do these 
oib undergo by exposure to the air ? What causes oils to become rancid ? 
In what manner do these oils sometimes produce spontaneous combustion? 



VEGETABLE OILS 



343 



which plants are distinguished from each other in a concen- 
trated state. These oils are soluble in alcohol, and very 
sparingly so in water. When dissolved in the former, they 
constitute essences^ a great variety of which are manufac- 
tured, particularly in Paris, and sold as perfumes in most 
parts of the world. 

All the volatile oils, when pure, pass away by e /apora- 
tion. Hence, a good test of the purity of these oils is to let 
a drop fall on paper, and if ^nj oily spot is left, after waiT*. 
ing the paper, the essential oil has been adulterated by some 
fixed oil. 

The essential oils burn with a clear, white Hght, and the 
only products of their combustion is water and carbonic acid. 
Hence, these oils are composed solely of carbon and hydro- 
gen, the water and carbonic acid being formed by the 
absorption of oxygen to support the combustion. 

On exposure to the atmosphere they absorb oxygen, and 
in consequence become thick, and turn of a yellowish color. 
They are at length converted into solids resembling resins. 
Some of them during this process deposit crystals, when 
exposed to the agency of light. 

Volatile oils do not unite readily with metallic oxides, and 
even with alkalies, no combination is readily effected. They 
dissolve sulphur in large quantities, forming the well known 
article called balsam of sulphur. 

The following list contains the principal essential oils, 
with their colors and specific gravities annexed. 



OILS OP 

Turpentine 

Lemons 

Anise , 

Juniper 

Chamomile 

Caraway 

Lavender 

Peppermint 

Rosemary 

Camphor 

Mint . 

Cinnamon 

Cloves . 

Sassafras 

Mustard 

Bitter Almonds 



COLOR. SPECIFIC GRAVITY. 

Colorless 0.870 

Pale yellow 0.850 

do. do 0.985 

Greenish yellow .... 0,911 

Deep blue 0.940 

Pale yellow 0.940 

Yellow 0.870 

Greenish yellow .... 0.920 

Colorless 0.895 

White . 0.988 

Greenish 0.975 

Yellow 1.035 

Pale yellow 1.061 

Red, or yellow 1.094 

Yellow 1.038 

Colorless 1.043 



In the above table, water, as formerly explained, is esti- 
mated at 1000. Most of these oils, it will be seen, are 
lighter than water, while a few, as oil of cloves, are heavier 



344 RESINS. 

than that fluid. It is hardlj necessary to describe the pro 
parties of these oils separately, as they are all in manj 
respects quite similar. The odors of many of them are weli 
known, and their tastes familiar to most persons who indulge 
in the use of candy. There are, however, a few of them 
whicl differ greatly from the rest of the class, and particij 
larly 

OIL OF BITTER ALMONDS. 

When the bitter almond is reduced to a pulp and com- 
pressed, a pure fixed oil is obtained, but when the pulp is dis- 
tilled with water, a volatile, poisonous oil passes over, which 
smells strongly of hydrocyanic acid. Neither this volatile 
oil, nor the hydrocyanic acid seem to exist in the almond, 
but are developed by the action of the water during distil- 
lation. After being purified from the volatile and hydrocy- 
anic matter, and a second time distilled from off pulverized 
lime, the oil is a colorless, volatile liquid, with a burning, 
aromatic taste. When suddenly heated in the open air, il 
takes fire, and burns with flame. In this state it is a com- 
pound of hydrogen with a substance called hcnzule; which^ 
combining with oxygen, forms benzoic acid. 

Benzule combines with a variety of simple bodies, form 
ing the compounds chloride of benzule^ bromide of benzule, 
iodide of benzule, &c., the elements of which will be known 
by then* names. 

Oil of Turpentine. — The pure essence of turpentine, or 
camphene, forms an interesting compound with the hydro- 
chloric acid called, artificial camphor, consisting of 2 eq. of 
camphene, and 1 eq. of acid. It is formed by transmitting 
a current of dry hydrochloric acid through the camphene, 
which has been recently and carefully distilled ; the vessel in 
which it is contained being surrounded with a mixture of 
snow and salt, a quantity of the gas is absorbed, the liquid 
acquires a deep brown color, and a white crj'stalHne, vola.- 
tile substance, similar in its properties to camphor, remains. 

RESINS . 

The resins are peculiar substances which exude from cei- 
tain trees, or plants, or are contained in their juices. They 
commonly contain a portion of the essential oil of the plant. 
They are sohd at common temperatures, and, when rubbed, 

What are the resins ? In what liquid are the resins soluble ? 



FERMENTATION. 345 

show signs of electrical excitement. Tbeir coiors are ycl 
low, reddish, and white, and most of them are translucent, 
or transparent. 

The resins are soluble in alcohol, ether, and the essential 
oils, but are precipitated by water, in which they are entirely 
insoluble. They are dissolved, and at the same time decom- 
posed, by the sulphuric acid, with evolution of sulphurio 
acid gas, and the deposition of charcoal. 

The principal resins are, common resin, gum, copal, lac, 
mastic, elemi, and dragon's blood. Common resin, called 
rosin^ is w^hat remains after the distillation of spirit of tur- 
pentine. The turpentine itself is obtained by making in- 
cisions in the fir tree, from which it exudes. This consists 
of resin, and the oil of turpentine, which are separated by 
distillation. 

The uses of many of the resins are well known. Sealing 
wax is made of lac, turpentine, and common resin. Copal 
and elemi, when dissolved in spirit of turpentine, or alcohol, 
form varnishes. 

FERMENTATION. 

Fermentation consists in a spontaneous exercise of chem- 
ical affinity, in a vegetable substance, or solution, in conse- 
quence of which its properties are materially or totally 
changed. 

There are several kinds of fermentation, the names oi 
which indicate the products formed. These are, the sac- 
charine^ the vinous^ the acetic^ and the putrefactive. 

The product of the first is sugar ; that of the second, 
wine ; that of the third, vinegar ; while the fourth results 
in the total decomposition of all vegetable matter, and the 
destruction of every useful product. 

Saccharine Fermentation. — The germination of seeds, and 
the malting of barley, are instances of the saccharine fer- 
mentation, the farinaceous being converted into saccharine 
matter, or sugar. 

Vinous Fermentation. — This, by the generality of man- 
kind^ is considered the most important of all fermentations, 
since, from the days of Noah and Alexander, to the pre 



Why are the resins precipitated by water ? What are the names of the 
principal resins ? In what manner is common resin, or rosin, obtained * 
What are the uses of some of the principal resins ? What is fermentation ? 
What are the different kinds of fermentation ? What is the product of the 
saccharine fermentation ? What is tl p oduct of the vinous ? 
15* 



34b FERME.N TATiO^^ . 

sent time, its product has been employed, either to heighten 
the pleasures, or as an antidote to the cares of this poor life. 

Wine, as well as other intoxicating liquors, are produced 
only by the vinous fermentation ; a process by which alco- 
hol is formed. There are four conditions necessary to the 
success of this process. These are, the presence of water, 
sugar, and yeast, in mixture, and a temperature between 
60 and 70 degrees. Or, instead of yeast and sugar, sac- 
charine matter, and starch, or the sweet juices of fruits. 
These conditions, being united, there succeeds a brisk intes- 
tine motion, attended with the escape of carbonic acid gas in 
abundance, and at the same time the transparency of the fluid 
is diminished by the rising of opaque filaments, the whole 
being attended with an elevation of temperature. When 
these phenomena cease, the liquor is found to have lost its 
sweet, mucilaginous taste, and to have acquired some de- 
gree of acidity, with a brisk, penetrating flavor, and the 
power of producing intoxication. 

Chemical changes in fermentation. — In respect to the 
chemical changes which take place during this process, it 
is found that after the fermentation, the sugar has entirely 
disappeared, and that it is replaced by a quantity of alcohol, 
none of which existed in the liquid before the process. 
Hence, sugar is converted into alcohol hy the vinous fermen- 
tation. But the weight of the alcohol is never equal to the 
weight of sugar employed, by nearly one half This loss is 
accounted for by the escape of the carbon and oxygen of the 
sugar, in the form of carbonic acid. When the process is 
conducted in such a manner that the quantity of carbonic 
acid can be retained and weighed, it is found to coiTespond 
precisely with the loss of the alcohol ; that is, the combined 
weight of tho acid and alcohol are equal to that of the sugar. 
This may be made apparent thus : Sugar and alcohol are 
composed of 

Sugar. Alcotol. 

3 eq. of carbon, 18 2 eq. carbon, 12 
3 do. of hydrogen, 3 3 do. hydrogen, 3 
3 do. of oxygen, 24 1 do. oxygen, 8 

45 23 



What is the product of the acetic ? What are the results of the putrefac- 
tive fermentation? What changes do seeds and barley undergo by germination 
and malting? What are the four conditions necessary to induce the vinous 
fermentation '' What gas escapes during this fermentation ? 



ALCOHOL. 347 

This shows a loss of one proportion of carbon and two 
proportions of oxj^gen from the sugar, the alcohol contain- 
ing onh^ two parts of carbon and one of oxygen, while the 
sugar contained three of carbon and three of oxygen, the 
proportion of hydrogen being the same in both. The differ- 
ence between the number for sugar and that for alcohol is, 
therefore, 22. Now, we have seer that carbonic acid is 
composed of one proportion, or atom, of carbon, 6, and two 
proportions, or atoms, of oxygen, 16, and these two num- 
bers make the precise quantity of carbon and oxygen lost 
bv the sugar, and which is not contained in the alcohol. 
Therefore, 45 parts of sugar produce, by fermentation, 23 
parts of alcohol, which is found in the fermented hquor, and 
22 parts of carbonic acid gas, which escape. 

This investigation, while it affords a beautiful illustration 
of the doctrine of definite proportions, demonstrates that 
nothing is lost by a new an-angement, or interchange of 
elements. 

It is beheved, that the vinous fermentation never takes 
place without the presence of sugar, the elements of this 
ingredient, as shown above, furnishing by decomposition 
those of the alcohol. In cases where substances which 
contain no sugar are known to produce alcohol without the 
addition of this ingredient, the process is explained by the 
supposition that the starch which these substances contain, 
is converted into sugar by the saccharine fermentation. It 
is well known that potatoes, which contain httle or no 
sugar, yield a large quantity of alcohol by fermentation. 
But potatoes contain a large proportion of starch, which 
entirely disappears during the process, being first converted 
into sugar, and then into alcohol. 

ALCOHOL. 

When a hquor which has passed through the vinous 
fermentation is distilled, there rises from it a fluid, having 
much more highly intoxicating powers than the fermented 
liquor from which it is obtained. This liquor has a sharp 
penetrating taste, and retains the flavor and odor of the fer- 

What becomes of the sugar during the vinous fermentation ? Is the we'ght 
of alcohol formed, equal to the weight of sugar employed? What becomes 
of the deficiency ? What is the composition of sugar ? What is the compo- 
sition of alcohol ? How does it appear that the loss from the sugar escapes 
in the form of carbonic acid ? Does the vinous fermentation ever take place 
without the presence of sugar ? How is the process explained in cases 
where alcohol is formed by substances containing no sugar, as in potatoes ' 
How are spirituous liquors obtained ? 



343 WIJNK. 

merited liquor, from which it is distilled. The fluid so 
obtained is alcohol mixed with water, and containing a por- 
tion of the essential oil pecuHar to the vegetable which 
formed the fermentative solution, and which gives it a flavor. 
Thus, brandy^ rum^ and whishey^ have each a flavor of theii 
own, which arises from this circumstance. These are called 
spirituous liquors. 

When a spirituous liquoi is distilled, the alcohol is ob- 
tained in a state of much gi'^ater purity, the oil which it 
contained and most of the water being left in the retort, or 
still. In this state it is colorless, highly inflammable, produ- 
ces cold by evaporation, and occasions a considerable aug- 
mentation of temperature by admixture with water. 

Common alcohol contains a portion of water, and has a 
specific gravity of from 850 to 875, water being 1000. It 
may be further purified, or freed from water, by adding to it 
warm carbonate of potash, or muriate of lime, which com- 
bines with the water, and sinks to the bottom of the vessel, 
after which the alcohol may be poured off. Very pure 
alcohol may also be procured, by putting it into a bladder, 
which being suspended in a warm place, the water will 
slowly pass through the coats, while the pure alcohol is 
retained. The strongest alcohol which can be procured by 
either of these methods, has a specific gravity of 800, or 
796, at the temperature of 60°. 

Pure alcohol has never been frozen, though exposed to 
the lowest temperature which art has ever produced. It is 
a powerful solvent, being capable of dissolving camphor, 
resins, soap, volatile oils, sugar, balsam, &c. 

Pure alcohol has precisely the same properties from what- 
ever substances it is obtained. 

WINE. 

Wine, properly so called, is exclusively derived from the 
fermented juice of the grape. The principal substances in 
this juice, are sugar, gum, gluten, and hitartrate of potash. 

This liquid readily passes through the vinous fermenta- 
tion, without any addition, or spontaneously, at temp.ra- 

What gives the peculiar flavor to distilled liquors, as brandy, rum, and 
whiskey? How is alcohol obtained? Do spirituous liquors yield pure alco- 
hol on distillation ? What is the specific gravity of common alcohol? How 
may pure alcohol be ol)tained ? What is the specific gravity of the purest 
alcohol ? What is said of the freezing of pure alcohol ? What is said of the 
boivent powers of alcohol ? 



WINE. 349 

tures between 60° and 80°. After fermentation, the spe- 
cific gra\dty of the hquid is diminished, its flavor is entirely 
changed, and it is found to contain exciting or intoxicating 
quahties, from the formation of alcohol, of which, before 
this process, it contained not the slightest trace. Alcohol 
IS, therefore, the product, or creation, of the vinous ferment- 
ation. 

A question naturally suggests itself here, says Prof 
Brande, why the juice of the grape does not ferment in the 
fruit itself? We know that ripe grapes, even when cut 
from the vine, exhibit no such tendency ; they dry up, and 
shrivel, becoming raisins, but never fermenting, so long as 
the skin is entire. It was once supposed that this arose 
from the gluten, or ferment being in distinct vesicles, or cells, 
from those containing the saccharine juice, and that conse- 
quently fermentation could not ensue, till the fruit was 
mashed or broken, so as to mix these ingredients. But Gay 
Lussac found that when grapes were bruised, and carefully 
excluded from the air, no change ensued ; but that even a mo- 
mentary exposure of the pulp to the air, or oxygen gas, was 
enough to communicate to it the power of fermentation. 
This seems to arise from some recondite action of oxygen 
on the glutinous principle of the grape, by absorbing which, 
it acquires the properties belonging to yeast. It is curious 
how perfectly the exclusion of air is provided for by the 
natural texture of the grape skin, which does not allow its 
ingress in the smallest degree, though it admits of the trans- 
piration of the aqueous vapor, as is shown by the desicca- 
tion of the fruit. 

It is well known that there is a great variety of wines, 
which differ from each other in color, flavor, and strength, 
as well as in price. These differences depend on various 
circumstances, as purity, scarcity, fame, and real qualities, 
for in the latter respect, there are certainly great and mate- 
rial differences. Some wines will not keep through the hot 
season, or in a hot climate, without such an addition of 
brandy as to injure, or spoil the original flavor and purity 
of the hquor ; others have a fine flavor, and have naturally 
sufficient alcohOx to preserve them in any, or all parts of 
the world. 



ALCOHOL. 



All wines contain more or less alcohol, which, as above 
stated, is the product of the vinous fermentation. It was 



350 ALCOHOL. 

formerly denied, however, that the alcohol pre-existed in the 
wine, but that it was the product of distillation. Its ele- 
ments, it was urged, did exist in the wine, but that they 
were brought together to form the alcohol by the heat of dis- 
tillation, and then raised and separated from the wine by a 
continuance of the process. The inference of this belief has 
been, that he who drank wine, did not of course take any 
portion of alcohol, this depending on the fact, whether any 
had been added to the wine. But that wine, and in truth, 
all fermented liquors contain alcohol, and that this is the 
product of fermentation, is shown by the fact, that the juice 
of the grape, or other fermentative hquors, contains no alco- 
hol until after having passed through that process, and that 
after this, alcohol can be separated from it without distilla- 
tion, or the use of heat in any w^ay. 

METHOD OF OBTAINING ALCOHOL WITHOUT 
DISTILLATION. 

For this purpose, either wine, cider, or beer, may be se- 
lected, the experimenter being satisfied, that no alcohol has 
been added to the liquor, to be used in the experiment. 

A glass tube, say half an inch in diameter, and two feet 
long, being procured, fill it about half full of the liquor to 
be tried. Then drop into the hquor pieces of carbonate of 
potash, which has previously been well dried by heat. Con- 
tinue this until all the water has been taken up and incor- 
porated with the alkah, when the alcohol will gradually 
rise to the upper portion of the tube, and stand in a distinct 
stratum on the other contents. By graduating the tube 
into 100 equal parts, by pasting on its outside a strip of 
paper thus divided, the percentage of the alcohol in different 
kinds of wine may at once be determined. It is difficult, 
however, if not impossible, to extract all the alcohol by this 
method, since the quantity of alkali necessary to absorb all 
the water, tends to thicken the liquid, and thus prevent some 
of the particles of alcohol from rising through it. While 
therefore, this method serves to show beyond all doubt, that 
the alcohol exists in the wine before distillation ; yet when 
the experimenter designs to obtain the whole quantity of 
alcohol in any liquid, the only sure method is, after satura- 
ting the wine, or other beverage, with lime, or potash, to 
use a gentle heat ; and a long necked glass retort, reaching 
a good distance into the receiver, is the best apparatus. 



ALCOHOL. 



351 



PROPORTIONS OF ALCOHOL IN DIFFERENT WINES. 

The following Table, from Brande's Manual of Chem- 
istrj, exhibits the proportion of alcohol, specific quantity of 
0.825, at 60°, by measure, existing in 100 parts of the 
several kinds of wine and other liquors. 



PER CENT. OF ALCOHOL BY MEASURE. 



Lissa, 
do. . 



Average, 

Raisin wine, . 

do 

do 

Average, 



26.47 
24.35 
25.41 

26.40 
25.77 
23.20 
25.12 



3. Marsala, 26.03 

do 25.05 

Average, . . . 25.09 



4. Port, 
do. 
do. 
do. 
do. 
do. 
do. 



Average, 



25.83 
24.29 
23.71 
23.39 
22.30 
21.40 
19.00 
22.96 



5. Madeira 24.42 

do 23.93 

do. (Sercial,) . . . 21.40 

do 19.24 

Average, . . . 22.27 

6. Currant wine, . . . 20.55 

7. Sherry, 19.81 

do 19.83 

do 18.79 

do 18.25 

Average, . . . 19.17 

8. Teneriffe, 19.79 

9. Colares, 19.75 

10. Lachryma Christia, . 19.70 

11. Constantia, white, . . 19.75 

12. do. red, . . 18.92 

13. Lisbon, 18.94 

14. Malaga, ...... 18.94 

15. Bucellas, 18.49 

16. Red Madeira, . . . 22.30 
do 18.40 

Average, . . . 20.35 



34. 



Cape Muschat, 
Cape Madeira, . 

do. . . . 

do. . . . 

Average, . 

Grape wine, 
Calcavella, . . 
do. ... 
Average, . 

Vidonia, . . . 
Alba Flora, . . 
Malaga, . . . 
White Hermitage 
Rousillon, . . 
do. ... 
Average, . 

Claret, . . . 

do 

do 

do 

Average, . 

Zante, . . . 

Malmsay Madeira. 

Lunel, 

Sheraaz, . 

Syracuse, 

Santeme, 

Burgundy, 

do. . . 

do. . . 

do. . . 
Average, . . 

Hock, .... 
do 

do. (old in casks 
Average 



35. Nice, 



18.25 
22.94 
20.50 
18-11 
20.51 

18.11 
19.20 
18.10 

18.65 

19.25 
17.26 
17.26 
17.43 
19.00 
17.26 
18.13 

17.11 
16.32 
14.08 
12.91 
15.10 

17.05 
16.40 
15.52 
15.52 
15.28 
14.22 
16.60 
15.22 
14.53 
11.95 
14.57 

14.37 
13.00 

8.88 
12.08 

14.68 



352 



ETHER. 



TABLE OF THE PROPORTIONS bF ALCOHOL — Concluded. 



36. Barsac, 13.86 

37. Tent, 13.30 

38. Champagne, (still,) . 13.80 

do. (sparkling,) 12.80 

do. (red,) . . 12.56 

do. do. . . 11.37 

Average, . . . 12.61 



39. Red Hermitage, . 


. 12.32 


40. Vin de Grave, . . 


. 13.94 


do. .... . 


. 12.80 


Average, . . 


. 13.37 



41. Frontignac, (Rivesalte,) 12.79 

42. Cote Rotie, .... 12.32 

43. Gooseberry wine, . 11.84 

44. Orange wine, . . . 11.26 

45. Tokay, 9.88 



46. Elder wine, .... 8/9 

47. Cider, (highest average,) 9.37 



do. (lowest,) 

48. Perry, (average,) . 

49. Mead, 

50. Ale, (Burton,) . . 
do. TEdinburgh,) . 
do. (Dorchester,) . 

Average, . . 



5.21 
7.26 
7.32 
8.88 
6.20 
5.56 
6.87 



51. Bro\\ai stout, . . . 6.80 

52. London Porter,(average,) 4.20 

53. do. (small Beer,) 1.28 

54. Brandy, 53.39 

55. Rum, 53.68 

56. Gin, 57.60 

57. Scotch Whiskey, . . 54.32 

58. Irish do. . . . 53.90 



"The wines," sajs Professor Brande, "employed in the 
experiments upon which the preceding table is founded, 
were selected with all possible caution as to purity and 
quality; a given measure of each (saturated, when neces- 
sary, with lime, or potassa,) was carefully distilled nearly 
to dryness, and the bulk of the distilled product was exactly 
made equal to that of the original wine, by the addition of 
distilled water. After 24 hours, its specific gravity was 
determined, and thence the quantity of alcohol, by refer- 
ence to Gilpin''s Tables.'''' 



The name ether was originally applied to a highly fragrant 
and volatile liquid, obtained by the distillation of alcohol 
with sulphuric acid. But it has been found that the same 
substance, when distilled with other acids, affords a liquid 
possessing in some respects similar properties, and therefore 
these compounds are now distinguished by prefixing the 
name of the acid employed. 

Sulphuric Ether. — To make sulphuric ether, pour into a 
tubulated retort a certain quantity of alcohol by weight, and 
add, in small portions at a time, the same weight of strong 
sulphuric acid, allowing the mixture to cool after each addi- 
tion. Then connect the retort with a receiver, and, by 
means of a lamp, make the mixture boil. The receiver must 



How is ether obtained ? 
ether ? 



What is the process of obtaining sulphuric 



ETHER. 35> 

be kept cold by the application of ice, or wet cloths. The 
ether will pass over and be condensed in the receiver. The 
ether thus obtained, contains a portion of alcohol, and com- 
monly a little sulphuric acid, from which it is purified by 
agitation with potash, and re-distillation. 

In respect to the' chemical changes which take place 
between the alcohol and acid, to form the new product 
ether, it is found, on analj^sis, that the latter substance is 
composed of two proportions of defiant gas, and one propor- 
tion of water. The number for defiant gas being 14, and 
that for water being 9, the equivalent number for ether is 37. 

Now, defiant gas consists of 2 atoms of carbon, 12, and 
2 atoms of hydrogen, 2=14, to which 1 atom of water, 9, 
being added, makes the composition of ether. 

Alcohol is composed of, or contains the elements of, 1 
atom of defiant gas, and 1 atom of water, and therefore al- 
cohol contains double the proportion of water that ether 
does. Now, if 1 proportion, or atom of water, be abstracted 
from two of alcohol, the exact proportions constituting ether 
will remain. Thus, the number for alcohol being 23, double 
this number is 46, from which one atom of water, 9, being 
taken, there remains 37, the number representing ether. It 
will be seen, on comparing these several numbers, that they 
exactly correspond with the constituents above named, and 
it is supposed that this is the precise mode in which sul- 
phuric acid operates to convert alcohol into ether. In con- 
sequence of the affinity of sulphuric acid for water, it 
abstracts one atom of that fluid from the alcohol, and thus 
the elements of ether remain. 

Sulphuric ether is a hght, odorous, transparent fluid, of a 
hot and pungent taste. Its specific gravity, when most pure, 
is about 700, water being 1000 ; but that of the shops is 740, 
or 750, owing to the presence of alcohol. When exposed 
to the open air, it evaporates with great rapidity, and occa- 
sions an intense degree of cold. This is in consequence of 
the principle already explained, that when a substance 
passes from a denser ,to a rarer state, caloric is absorbed. 

Ether is exceedingly combustible, and burns with a blue 

What is the composition of sulphuric ether? Explain the difference be- 
tween alcohol and ether, and describe the change by which the former is 
converted into the latter. What is the specific gravity of ether when most 
pure ? How does ether occasion an intense degree of cold ? Why does the 
evaporation of ether occasion cold ? 



354 VEGETABLE ALKALOIDS. 

flame, the product of its combustion being water and car- 
bonic acid. 

Ether is employed as a medicine in nervous fevers, and 
as a solvent in the arts. When pure, or when that of the 
shops is agitated with water, and, after standing a while, is 
poured off, it is a solvent of India rubber, one of the most 
insoluble of vegetable products. 

Nitrous Ether is prepared by distilling alcohol with nitric 
acid, in a manner similar to that described for sulphuric 
ether, to which its leading properties are similar. It is, 
however, still more volatile, and is subject to decomposition 
by keeping. 

VEGETABLE ALKALOIDS. 

The vegetable alkalies, as they were formerly called, as 
potash and soda, are obtained by the destruction and incine- 
ration of the vegetables in which they exist. The bases of 
these, as we have seen, are metals, and have already been de- 
scribed by the names of potassium and sodium. The alka- 
loids, on the contrary, are obtained, not by use of fire, but 
by maceration in pure water. 

The following is an outhne of the method by which they 
are obtained. In the first place^, the substance containing 
the alkaloid is digested in a large quantity of water, the 
purer the better, which dissolves the salt, the base of which 
is the alkali. On adding some salifiable base, such as potash, 
or ammonia, which has a strong affinity for the acid of the 
vegetable salt, in the watery solution, this salt is decom- 
posed, its acid combining with the potash, or ammonia, and 
thus leaving the vegetable alkali in the solution. This al- 
kali being insoluble in water, while the new salt formed by 
the acid of the vegetable, with the potash, or ammonia 
added, is soluble, the former is obtained by filtering the whole, 
by which the alkaloid is detained, while the water contain- 
ing the solution of salts passes the filter. 

The alkaloids are all composed of carbon, hydrogen, oxy- 
gen, and nitrogen, as ultimate principles ; but in the state 
above described, they contain several impurities, such as olea- 
ginous, resinous, or coloring matter, with which they are com- 

What are the uses of sulphuric ether? How is nitrous ether procured? 
How does the nitrous differ from the sulphuric ether ? How do the oxides 
of potassium and sodium differ from the vegetable alkaloids? How are the 
vegetable alkaloids obtained ? Give an outline of the process by which 
these substances are procured ? 



ALKALOIDS. 355 

biued in the plant. To purify them from ihest they are 
mixed with a Httle animal charcoal, which deprives them of 
color, and then dissolved in boiling alcohol, in which all the 
alkaloids are readily soluble. This solution is filtered while 
hot, and yields the pure alkaloid, in the solid form of fine 
crystals, either on cooling, or by evaporation. 

The following hst contains the principal alkaloids, to- 
gether with the plants from which they are obtained. Their 
exact compositions we have not thought necessary to detail, 
their ultimate principles being, as stated above, various pro- 
portions of oxygen, hydrogen, carbon, and nitrogen. The pro- 
perties of the most important of these will be described. 



TABLE OF THE ALKALOIDS, WITH THE VEGETABLES 
FROM WHICH THEY ARE OBTAINED. 

ALKALOniS. PLANTS. 

Aconita Aconitum napellus, 

Aricina A bark from Africa, 

Atropia Atropa belladonna, 

Brucia Stryclmos nux vomica, 

Cinchonia Cinchona lancifolia, 

Codeia Opium, 

Conia Conimn maculatum, 

Corydalia Corydalis tuberosa, 

Cynapia ^thusa cynapium, 

Datura Datura stramonium, 

Delphia Delphinium staphisagn^la, 

Digitalia Digitalis purpurea, 

Emetia Cephaelis ipecacuanha, 

Hyoscyamia Hyoscyamus niger, 

Meconia . Opium, 

Morphia Opium, 

Narcotina Opium, 

Nicotina Nicotiana tobacum, 

Picrotoxia Menispermum cocculus, 

Cluinia Cinchona cordifolia, 

Sanguinaria Sanguinaria Canadensis, 

Solania Solanum nigrum, 

Narceia Opium, 

Thebaia Opium, 

Veratria Veratrum sabadilla. 

MORPHIA. 

This alkaloid is the medicinal agent in opium, in which it 
exists with meconic and sulphuric acids, and also with narco- 
tina, codeia, narceia, meconin, coloring matter, a fixed oil, and 
a Httle caoutchouc, or India rubber. In its pure state, mor- 

What are the most important vegetable alkaloids ? Wliat is morphia ? 



356 CINCHONIA. 

phia. exists in the form of brilliant prismatic crystals, which 
are transparent and colorless. It is insoluble in cold, and 
nearly so in hot water; but in strong alcohol, especially 
when hot, it dissolves freely, and without difficulty. 

Morphia is the narcotic principle in opium, but in the solid 
state, when pure, it appears, owing to its insolubility in 
water, to have little effect on the system ; but, dissolved in 
alcohol, it acts with great energy. 

There are several salts of morphia, as the acetate^ hy- 
drochlorate^ and sulphate. The acetate, though till lately 
much employed in medicine, is less convenient for that pur- 
pose than the hydrochlorate, being variable in composition 
and strength. 

NARCOTINA, 

This is easily prepared by digesting the aqueous extract 
of opium in sulphuric ether, in which meconate of morphia 
and morphia are insoluble, but which takes up all the nar- 
cotina, and deposits it in regular crystals by evaporation. 
The stimulating action of opium is, in part, ascribed to nar- 
cotina, and it is said that pure morphia acts more agreeably 
and safely than when narcotina is mixed with it. 

CINCHONIA. 

This is obtained from the bark of several species of cin- 
chona, or Peruvian harh.^ by which name it is more com- 
monly knowm. The process consists in taking up the 
soluble part of the bark with hot water, acidulated with 
hydrochloric acid. The solution, being concentrated by 
boiling, is then made alkaline by means of quicklime, when 
the cinchona is precipitated, and is re-dissolved in alcohol, 
and obtained by evaporation. 

Cinchona, thus obtained, is in the form of small crystals, 
which are insoluble in cold water, but dissolves in 2500 
times their weight of boiling water. 

With acids it forms several salts, among which is the 
sulphate, composed of 1 eq. cinchona, 156+1 eq. sulphuric 

What are the ingredients in opium besides morphia ? In what state dooa 
morphia exist in the opium? What is the process for obtaining morphia? 
What is the use of the magnesia in this process ? What are the solvents of 
morphia? In what state is morphia used in medicine? Why is it not used 
in its pure state? What advantage has morphia over opium as a medicine? 
How is narcotine obtained ? Is narcotine soluble in water ? What are the 
solvents of narcotine ? What effects of opium are imputed to narcotine ? 



VERATRIA. 357 

acid, 40z= 196, eq. for sulphate cinchona. It is employed in 
medicine. 

QUINI A. 

Quinia, or quinine, is also obtained from the bark of cin- 
chona, by a process similar to that described above. It is 
in the form of a white powder, hardly ever assuming the 
crystahne form, though verging towards it when obtained 
by means of boihng alcohol. It is extensively employed in 
the practice of medicine, being a decided febrifuge, espe- 
cially in cases of fever and ague. 

The most important salt of quinia is the sulphate, which 
is very largely manufactured for medicinal purposes, and 
from its commercial value is often largely adulterated. 

Sulphate of quinia is composed of 2 eq. quinia, 328+1 
eq. sulphuric acid, 40=368. 

STRYCHNIA. 

This alkaloid is extracted from the strychnos nux vomica^ 
a kind of nut, well known to apothecaries as a poison. It 
is prepared by treating powdered nux vomica with cold 
water, and afterwards evaporating to the consistence of a 
syrup ; alcohol is then added, which takes up the strych- 
nia, from which it is precipitated by lime. 

The alkaloid, thus obtained, is in the form of minute quad- 
rangular prisms. It is nearly insoluble in cold water, but 
still excites an intolerable bitterness in the mouth. It is one 
of the most virulent poisons known, containing the essence 
of the deleterious, properties of the nux vomica. 

VERATRIA. 

Veratria is obtained by a similar process to that above 
described for strychnia. It is contained in several plants of 
the hellebore tribe, known to botanists under the name of 
veratrum, one species of which is common in swampy places, 
well known by the appellation of itch-root. It acts with 
most disagreeable energy on the membrane of the nose, pro- 

What is said of the efficacy of cinchonia and quinia in the cure of fevers • 
What relation do cinchonia and quinia appear to bear to each other? In what 
species of bark do these alkalies exist ? By v^hat process are these substances 
obtained ? What is the appearance of cinchonia? How do the alkaline pro- 
perties of cinchonia appear? What salts does it form with acids ? What 
is the appearance of quinia? What is the solvent of quinia ? In what form, 
is quinia employed in medicine ? What is the appearance of sulphate of 
quinia, and what its composition ? 



358 ANIMAL CHEMISTRY. 

ducing violent sneezing, though in very minute quantity. 
If taken internally, it is a prompt and active poison. 

EMETE A. 

This is obtained from the root of ipecacuanha, by diges- 
tion in water, and the subsequent use of alcohol, as already 
described for the other alkaloids. It is a white pulverulent 
substance, of a bitter, disagreeable taste, sparingly soluble 
in cold, but more freely in hot water. It is the cause of the 
emetic properties in the ipecacuanha, of which it contains 
about 1 6 per cent. The other alkaloids are extracted from 
the several plants named at the head of this article, by 
means similar to those already described ; but most of them 
being inert, and useless, it is hardly necessary to go through 
their descriptions at this place. 

ANIMAL CHEMISTRY. 

In relation to chemistry, the circumstances which distin- 
guish animal from vegetable substances are, the large quan- 
tity of nitrogen which the former always contain, their strong 
tendency to putrefaction, and the offensive products which 
they exhale during decomposition. 

Animal substances are essentially composed of carbon, 
hydrogen, oxygen, and nitrogen ; and in addition to these, 
they sometimes contain sulphur, phosphorus, iron, and small 
quantities of saline matter. 

Fibrin. — The lean parts of animals consist chiefly of 
fihrin. This may be separated and observed in its pure 
state, by removing the soluble parts of lean beef, cut into 
small pieces, by repeated washing, and digestion in cold 
water. 

Fibrin thus obtained, is nearly white, and is insipid and 
inodorous. It readily passes into the putrefactive fermenta- 
tion, but in thin pieces, suspended in a dry place, its fluid 
parts evaporate, and it becomes hard, brittle, and translu- 
cent. 

Alcohol converts fibrin into a fatty substance, which is 
soluble in the same fluid, and in ether, but is precipitated 
by the addition of water. This substance is decomposed 
by all the strong acids, and is dissolved by caustic potash. 

In relation to chemistry, what are the circumstances which distinguish 
animal from vegetable substances ? What is the essential composition of 
animal substances ? What is fibrin? How may fibrin be obtained? What 
are the properties of fibrin ? 



ANIMAL CHEMISTRY. 359 

Fibrin is composed of 18 parts of carbon, 1 4 of hydrogen, 
5 of oxygen, and 3 of nitrogen. 

Albumen. — Albumen enters largely into the composition 
of animals. Their sohd, as well as fluid parts, contain it 
in greater or less proportion. Liquid albumen is nearly pure 
in the whites of eggs. Its appearance, and manjr of its pro- 
perties, in this state, are well known. It is coagulated, and 
converted into a soft sohd, by heat, by alcohol, and by the 
stronger acids. The character of being coagulated by heat, 
distinguishes albumen from all other animal fluids. It is 
completely soluble in cold water, and it is said that when 
this fluid contains only toW part of albumen, it becomes 
opalescent by boiling. On this property is founded the 
clarifying effects of albumen. As it coaglates, by the 
heat of the water, it entangles any insoluble particles the 
fluid contains, and rises with them to the surface. 

Gelatine. — This substance forms a proportion of all the 
solid parts of animals, and is particularly abundant in the 
skin, tendons, membranes, and bones. It is soluble in boil- 
ing water, and forms a bulky, semi-transparent, tremulous 
mass when cold. By evaporation, it becomes a solid, 
brittle, hard, and semi-transparent substance, known in 
commerce and the arts, under the name of glue. This is 
chiefly prepared from the cuttings of skins, and the ears 
and hoofs of animals. Isinglass.^ which is the purest variety 
of gelatine, is prepared from certain parts of fish, and espe- 
cially the sturgeon. The gelatine called calves^ foot jellj^ 
is prepared by boiling the feet of that animal in water. 

Gelatine is precipitated by tannin. This is so delicate *» 
test for gelatine, that it is said, an infusion of nut gaiis, 
which contains a large quantity of tannin, will show the 
presence of gelatine when mixed with 5000 times its weight 
of water. 

The three ingredients, fibrin, albumen, and gelatine, form 
the most bulky parts of all animals, that is the flesh, ten- 
dons, cartilages, and skin. 

What is the composition of fibrin ? Where is albumen found nearly in a 
pure state ? By what agents is albumen coagulated ? By what property is 
albumeri distinguished from all other animal fluids ? How does albumen 
clarify liquids ? In what parts of animals is gelatine most abundant ? Under 
what name is dry gelatine known? What is isinglass 1 By what substance 
is gelatine precipitated from its solutions 1 What parts of animals are form 
ed by fibrin, albumen, and gelatine ? 



360 ANIMAL CHEMISTRY. 



OLEAGINOUS SUBSTANCES, 



The fat of animals is very analogous, in its composition 
and proportions, to the fixed, vegetable oils, its ultimate 
principles being carbon, hydrogen, and nitrogen. 

There is a considerable variety in the appearance and 
qualities of the fatty principle contained in different animals. 
The solid fat of land animals is called tallow, while the cor- 
responding substances from fish, which is fluid at com- 
mon temperatures, is called oil. 

All these substances agree very nearly in respect to com- 
position, the principal difference being in respect to form and 
appearance. Their uses, for making soap, giving light, 
&c., are well known. 



The blood of animals obviously consists of two parts, 
called serum and crassamentum. In healthy blood, these 
two parts separate spontaneously on standing. The cras- 
samentum coagulates, and forms a red, solid mass, while 
the serum surrounds it, in form of a yellowish fluid. 

Serum. — The serum contains a small quantity of soda in 
a free state, and is 29 parts in 1000 heavier than water. 
It consists, in part, of albumen, and is coagulated by heat, 
acids, and alcohol. The crassamentum consists of two 
parts, the fibrin and the coloring matter. The fibrin does 
not differ, except in form, from that obtained from lean 
flesh, which has already been described. 

The coloring matter of the blood consists of distinct par- 
ticles, which in birds and cold-blooded animals, are ellipti- 
cal in form, but in man, and other mammiferous animals, 
they are globular. These facts have been ascertained by 
means of the microscope. The globules are insoluble in 
the serum, but their color is dissolved by water, acids, and 
alcohol. 

Crassamentum. — It has been supposed that the crassa- 
mentum contained a portion of iron, but recent analysis has 
shown that this metal does not belong to the crassamentum 
as a whole, but only to the coloring matter ; for, when the 
fibrin is carefully separated from the coloring principle, it 

What are the ultimate principles of animal fats ? What difference is there 
between animal fats and animal oils ? In blood, what is the serum and what 
the crassamentum? What is serum composed of ? What does crassamen 
tum consist of? What does the coloring matter of blood con&^st of? 



RESPIRATION 361 

does not contain a trace of iron, while iron is always founa 
in the red globules. 

From the presence of iron in the globules, and its total 
absence in the other parts of the blood, it is inferred that the 
red color of the globules depend on the presence of this 
metal, though its quantitj^ is found to be only half a grain 
to a hundred grains of the globules. 

It is found that during the coagulation of blood, heat is 
evolved, and consequently its temperature is raised. This 
is owing to its passage from a rarer to a denser state, in con- 
sequence of which its capacity for caloric is diminished. 
We have had frequent occasions to refer to this principle. 
The increase of temperature from this cause, is liowever 
very slight, perhaps not more than two or three degrees ; 
but its cooling is considerably retarded by the caloric thus 
evolved. 

Cause of Coagulation. — The blood presents several phe- 
nomena, which neither the principles of chemistry nor physi- 
ology have been able to explain. The cause of it-3 coagu- 
lation, for instance, has never been satisfactorily accounted 
for. It does not arise from want of heat or motion, for if blood 
be drawn when the temperature of the air is equal to that 
of the animal from which it is taken, and then kept con- 
stantly in motion, its coagulation is not prevented, or even 
retarded. Indeed, neither moderate heat, nor cold, a vacuum, 
nor pressure, nor even dilution with water, seem to have 
any influence on the coagulation of the blood. On the 
contrary, its coagulation is prevented by certain causes, the 
effects of which could not be supposed to influence this 
circumstance. Thus, the blood of persons who have been 
destroyed by some kinds of poison, and by mental emo- 
tions, has been found uncoagulated, and in a fluid state. 
How causes so unlike should produce the same effects, or 
why either of them should affect the blood at all, are equally 
unknown. 

RESPIRATION. 

Respiration is the act of breathing, and consists in the 
alternate drawing into, and throwing out of the lungs, a 



On what metal does the coloring matter depend ? What proportion of iron 
is contained in the red globules of the blood? What is said concerning 
the heat evolved by the coagulation of the blood? What is said concerning 
the cause of the blood's coagulation? W^hat circumstances are said not to 
affect the coagulation of the blood? What circumstances are said to pr« 
vor;f the coagulation of the blood ? What is respiration? 
16 



56^2 RESPIRATION. 

quantity of atmospheric air. And it appears that this pro- 
cess, or an equivalent one, is necessary to support the hves 
of all animals. 

The atmosphere, as formerly shown, is composed of 80 
parts of nitrogen, and 20 parts of oxygen, and it is found by 
experiment, that no other gaseous compound can be substi- 
tuted for respiration, nor can these proportions be varied 
without injury to its qualities. 

The immediate effect of respiration is, to produce a change 
in the color of the blood as it passes through the lungs, thus 
indicating that it suffers some change in its properties at 
the same time. 

The -necessity of respiration to all warm blooded animals 
requires no proof ; and ^he necessity that the blood shoulA 
be brought into contact with the air inspired, is equally ob- 
vious from the organization of their lungs. 

Such animals are provided with two kinds, or classes Oi 
blood vessels, called veins and arteries. 

The arteries, particularly the large ones, are deeply seated 
within the animal, and convey the blood to all parts of the 
living system. The veins, on the contrary, especially the 
small ones, are situated near the surface, and are destined 
to convey the blood back to the heart, which had been 
thrown out by the arteries. 

But besides these two great systems of blood vessels, there 
is another system called the pulmonari/, which is destined 
expressly to convey the blood to the lungs, where it under- 
goes the change above mentioned, and then back again to 
the heart. 

Circulation of the Blood. — The entire circulation will now 
be readily understood. The blood being thrown to all parts 
of the body, is returned to the right side of the heart by the 
great system of veins. From the right side. of the heart it 
is sent to the lungs, by the pulmonary artery, and being 
there changed into arterial blood, is returned by the pulmo- 
nary veins to the left side of the heart. From the left side 



What is the composition of the atmosphere? What effect does a chanae 
in the composition or proportion of the elements of the atmosphere produce 
on respiration? What is the immediate effect of respiration on the color of 
the blood ? What is said of the necessity of respiration ? What are the two 
kinds of blood vessels called ? 'V^Tiere are the veins and arteries situated 
with respect to each other? What is the use of the arteries? What part oj 
the circulation do the veins perform ? What is the office of the pulmonarj* 
system ? Explain the entire circulation. 



RESPIRA-TIOI^. 1j53 

of the heart, it is thrown to all parts of the body oy the 
great sj^stem of arteries, to be returned to the right side by 
the veins, as before. 

When venous blood, fresh drawn, is suffered to stand a 
few minutes in a confined portion of atmospheric air, it is 
found that the air loses a part of its oxygen, which is re- 
placed by the same volume of carbonic acid gas, and at the 
same time the color of the blood, from being of a dark pur- 
ple, becomes florid red. This is the same change of color 
which the blood undergoes in its passages through the 
lungs. The cause of the change in the lungs might, there- 
fore, be inferred to be the absorption of oxygen by the blood, 
and the subsequent emission of carbonic acid. 

That this change of color in venous blood, when out of 
the lungs, is owing to the contact of oxygen, is shown by 
the more immediate production of the same effect when 
oxygen is substituted for atmospheric air, and also by the 
fact that no change of color is produced when the oxygen 
is entirely excluded. Hence, the inevitable conclusion, that 
fresh drawn venous blood emits a quantity of carbon in con- 
sequence of its coming in contact with oxygen, and that its 
change of color is caused by this emission. 

The same change thus proved to take place in the atmos- 
phere, is constantly going on in the lungs. The venous 
blood, which, as above explained, is sent to the lungs 
through the pulmonary artery, is charged with carbon, to 
which it owes its dark color. The oxygen of the atmos- 
phere, by inspiration, fills all the air vessels of the lungs, 
and is thus brought nearly into contact with the blood, 
being separated from it only by the thinnest membrane. 

It appears that through this membrane, the oxygen of the 
atmosphere is absorbed, and having combined with a portion 
of the carbon of the blood, it is again emitted in the form of 
carbonic acid gas, and to this process is owing the change 
from venous to arterial blood. 

Oxygen converted into Carbonic Acid. — In proof of this, 
experiment shows that when any living animal is confined 
in a portion of air containing a known quantity of oxygen 

From which side of the heart do the great arterief5 convey the blood to all 
parts of the body? How is the blood conveyed from the right to the left side 
ef the heart ? What effects do the contact of atmospheric air and venous 
blood produce on each ? How is it proved that the change of color in the 
blood is produced by the oxygen of the air ? What is the cause of the change 
of color in venous blood ? To what is the dark color of venous blood owing ? 



364 RESPJRATfOiN. 

gas. t}ie oxygen gradually disappears, and is replaced by the 
same quantity of carbonic acid. In ordinary respiration, the 
air from our lungs alwaj^s contains a portion of carbonic 
acid. This is proved by merely blov/ing into a glass ves- 
sel containing a solution of lime in water, or what is com- 
monly called lime water, when the clear water will instantly 
become turbid, because the carbonic acid from the lungs 
unites with the lime of the water, and forms an insoluble 
carbonate. 

It does not appear that the oxygen is absorbed, and 
retained by the blood ; for the absolute quantity of air, though 
many times respired by a confined animal, remains the same. 
This also proves that the nitrogen of the atmosphere is not 
absorbed. It is well known by experiment, that the conver- 
sion of oxygen gas into carbonic acid, does not in the least 
change its volume, but only adds to its weight. This ac- 
counts for the reason why the volume of air is not changed 
by respiration, or by conversion into carbonic acid, provided 
no absorption takes place. 

Change from Venous to Arterial Blood. — Thus the change 
from venous to arterial blood, seems to be produced entirely 
by the loss of carbon, which the former suffers while pass- 
ing through the lungs. 

It appears also, from numerous experiments, that not only 
warm blooded animals, but also fish, and cold blooded rep- 
tiles of the lowest order, absolutely require the presence of 
oxygen in order to sustain life. Water, it has already been 
stated, always contains a portion of this gas in a free state, 
and although the quantity is small, it is sufficient to sustain 
the lives of its inhabitants. That fish, frogs, and other ani- 
mals of this kind, cannot sustain life without oxygen gas, is 
proved by the fact, that they die in a short time, if the water 
in which they are placed is covered with a film of oil, so 
that no oxygen is admitted. Frogs, though capable of sus- 
pending their respiration for a long time, die in less than 
an hour, if the small quantity of water in which they are 

What change does the blood undergo in the lungs ? How is it proved tuat 
oxygen is converted into carbonic acid in the lungs ? How is it proved that 
we emit carbonic acid at every expiration ? In respiration, is the oxygen ab- 
sorbed and retained by the blood or not? How does it appear that neithei 
the nitrogen nor the oxygen of the atmosphere is retained in the process of 
respiration ? In what does the change from venous to arterial blood con- 
sist ? What is said of the necessity of oxygen to support the lives of cold 
blooded reptiles ? 



ANIMAL HEAT. • 365 

confined is covered with oil. Aquatic insects and worms 
exhibit the same phenomena v^^hen treated in the same man- 
ner. In these cases, experiment has shown that oxygen is 
converted into carbonic acid, the effect being the same as 
that produced bj the respiration of warm blooded animals. 
Indeed, the experiments of Spallanxani prove that ani- 
mals produce this change by the action of their skin. Thus, 
serpents, lizards, and frogs, during their torpid state, and 
when their respiration is suspended, still require small por- 
tions of oxygen, which they constantly convert into carbonic 
acid by means of their skin, and it is probable, that in this 
manner, the blood of these animals parts with a little carbon. 

ANIMAL HEAT. 

During combustion there is an absorption of oxygen, 
and a subsequent emission of carbonic acid gas, and in the 
act of respiration, oxygen disappears, and is replaced by the 
same acid gas. Combustion and respiration are therefore 
supported by the same principle, and yield the same product. 

This analogy led Dr. Black to conclude that the changes 
which take place on the air, and on the blood in the lungs, 
was the cause of animal temperature ; and several circum- 
stances, relative to the structure of animals, and the quantity 
of oxygen they consume by respiration, seem to show that 
the heat of their blood depends, in a measure at least, on the 
quantity of this principle thus consumed. Animals having 
the power to maintain their temperatures above the media 
in which they live, are provided with capacious lungs, and 
consume large quantities of oxygen. Birds, the temperature 
of whose blood is higher than that of man and quadrupeds, 
have lungs still more capacious, according to their size, and 
consequently, most probably consume more vital air. On 
the contrary, fish, frogs, and other animals of this tribe, 
which consume only very minute portions of oxygen, do 
not sustain their temperature above the media in which they 
live. 

It appears also, that the temperature of animals, when 
made to respire pure oxygen gas, is raised above the natural 
standard, but when the quantity of this gas consumed is 

How is it proved that fish and frogs require oxygen ? What effect does the 
skin of torpid animals have upon oxygen ? What analogy is there between 
combustion and respiration ? What is said concerning the quantity of ory- 
gen consumed by warm blooded animals ? What is said of the quantity of 
oxygen consumed by fish and frogs ? 



S66 ANIMAL HEAT. 

small, the temperature of the animal falls, and the circula- 
tion of the blood is sluggish and languid. 

From these considerations, it would appear that the heat 
of the animal is sustained by its respiration, and that its 
temperature is proportionate, in some degree, to the quantity 
of oxygen it consumes, or converts into carbonic acid. 

Dr. Crawford, pursuing this idea, supposed that the car- 
bonic acid discharged by the breath, being generated in the 
lungs, and accompanied with the loss of oxygen, extricated 
heat during its formation, and that the temperature of the 
animal might thus be explained. But as the heat of the 
lungs was found to be no greater than that of other internal 
parts, there must be some mode of accounting for its dis- 
tribution to other parts of the sj^stem, otherwise this theory 
could not for a moment be supported. It is obvious that, 
in whatever manner this distribution is effected, the heat 
must be latent, or insensible ; for, supposing it to be in a free 
state, the lungs or part where it is generated, would still 
be at a higher temperature than the parts to which it is 
distributed. 

Accordingly, on comparing the capacities of venous and 
arterial blood for heat, Dr. Crawford found, that arterial 
blood had the greatest capacity, and therefore, that at the 
same temperature, it contained a quantity of latent heat, 
which the venous blood did not. He therefore supposed 
that this latent heat was conveyed by the arterial blood, to 
all parts of the system, and as the arterial is gradually con- 
verted into venous blood, so the latent heat gradually be- 
came sensible, in all parts of the system, and that in this 
manner, animal temperature is maintained. 

This beautiful theory was supposed to be founded on the 
true principles of chemistry and physiology, and being so 
received, it accounts very satisfactorily for animal tempera- 
ture. But Dr. Davy has since shown that the principal 
fact on which it is founded, the difference of the capacities 
of venous and arterial blood for heat, is not true, but that 
in this respect there is Httle or no difference between the 
two kinds of blood. 

If Dr. Davy has maintained the truth, it is obvious that 
Dr. Crawford's theory must fall to the ground. 

Does it appear that there is any proportion between the heat of the ani- 
mal and the quantity of oxygen it consumes by respiration ? How did Dr. 
Crawford explain the cause of animal temperature ? Suppose arterial blood 
to have a greater capacity for heat than venous blood, on what circumstance 
could animal temperature be explained? 



ANIMAL HEAT. 367 

Although the facts stated above, in respect to the capacity 
of the hmgs, in warm blooded animals, and the quantity of 
oxygen which they consume, when compared with cold 
blooded animals, would seem to show almost beyond a 
doubt, that animal temperature is connected with the quan- 
tity of oxygen consumed, and the changes which the blood 
undergoes in the lungs ; still, some physiologists deny the 
agency of either of these causes in producing such effects 
and ascribe the evolution of animal heat entirely to the 
influence of the nervous system. 

The foundation of this doctrine is an experiment of Mr. 
Brodie, who found that on keeping up an artificial respira- 
tion in the lungs of a decapitated animal, the color of the 
blood was changed from purple to red, and carbonic acid 
emitted as usual; but that this animal grew cold more 
rapidly than another decapitated animal of the same kind 
which lay untouched. It is obvious that this result would 
follow unless heat was evolved by the artificial respiration, 
because the air forced into the lungs would abstract the 
heat of the animal. 

" Were these experiments rigidly exact," says Dr. Turner, 
"they would lead to the opinion that no caloric is evolved 
by the mere process of arterialization. This inference 
cannot, however, be admitted, for two reasons : — First, be- 
cause other physiologists, in repeating the experiments ot 
Brodie, have found that the process of cooling is retarded 
by artificial respiration ; and, secondly, because it is difficult 
to conceive why the formation of carbonic acid, which 
uniformly gives rise to increase of temperature in other cases, 
should not be attended, within the animal body, with similar 
results. It may hence be inferred, that this is one of the 
sources of animal heat." 

In respect to the influence of the nervous system over the 
development of animal temperature, there is no doubt but 
considerable effects may be safely attributed to this cause. 
But in what manner the heat is evolved, is perhaps uncer- 
tain. 

In conclusion we may remark, that the subject of animal 

How did Dr. Davy show that Dr. Crawford's theory was untenable ? "What 
is the foundation of the theory that animal heat is evolved by the nervous 
system ? If heat were not evolved by artificial respiration, why should this 
process cool the animal rapidly ? What are Dr. Turner's two reasons for 
supposing that Mr. Brodie's experiments are not conclusive, that heat is not 
evolved by respiration? Is it probable that the nerves affect the temperature 
of the animal ? 



368 ANALYTICAL CHEMISTRY. 

temperature has excited the attention, and has been made 
an object of experiment and research among philosophers 
and physiologists in all ages, and that many ingenious and 
some plausible theories have been invented and detailed, in 
order to give satisfactory explanation of its cause. The 
theory of Dr. Crawford, among these, was perhaps the most 
plausible, and certainly the most philosophical and beautiful. 
But we have seen, that the leading facts on which it was 
founded, have been proved by his successors not to be true, 
and therefore the theory itself cannot be maintained. That 
the oxygen of the atmosphere is one of the causes of animal 
heat cannot be doubted, from the facts, that no animal can 
live without it, and that the heat of animals is in some pro- 
portion to the quantity of this principle consumed. 

But as this principle can have no effect, except through 
the lungs, if it is admitted that heat is evolved by its action 
there, there is still much difficulty in explaining either why 
the lungs are not constantly at a higher temperature than 
the other parts of the system, or if they were, how the heat 
could be conveyed to the other parts, from its fountain. 

On the whole, it appears that the cause of animal heat is 
one of the arcana of nature, into which man has not yet been 
permitted to look, and therefore, we must be contented at 
present to attribute it to the vital principle. 



PART IV 



ANALYTICAL CHEMISTRY. 

To enter into a detailed account of experimental and ana- 
lytical chemistry, is altogether inconsistent with the design 
and limits of the present work. My sole object in this 
department is to give a few concise directions for conducting 
some of the more common analytical processes; and in 
order to render them more generally useful, I shall give exam- 



What is said in conclusion on this subject ? Has there been any theory 
proposed which accounts satisfactorily for the cause of animal heat? To 
what is it said must we at present attribute the cause of animal heat ? 



aiNalysis of gases. 369 

pies of the analysis of mixed gases, of minerals, and of 
mineral waters. 

ANALYSIS OF MIXED GASES. 

Analysis of Gaseous Mixtures containing Oxygen. — Of 
the various processes by which oxygen gas may be with 
drawn from gaseous mixtures, and its quantity determined, 
none are so convenient and precise as the method by means 
of hydrogen gas. In performing this analysis, a portion of 
atmospheric air is carefully measured in a graduated tube, 
and mixed with a- quantity of hydrogen, which is rather 
more than sufficient for uniting with all the oxj^gen present. 
The mixture is then introduced into a strong glass tube 
called Volta's eudiometer, and is inflamed by the electric 
spark, the aperture of the tube being closed by the thumb 
at the moment of detonation. The total diminution in vol- 
ume, divided by three, indicates the quantity of oxygen 
originally contained in the mixture. This operation may be 
performed in a trough either of water or mercury. 

Instead of electricity, spongy platinum (page 144) may 
be employed for causing the union of oxygen and hydrogen 
gases ; and, while its indications are very precise, it has the 
advantage of producing the effect gradually, and without 
detonation. The most convenient mode of employing it with 
this intention is the following. A mixture of spongy plati- 
num and pipe-clay, in the proportion of about three parts of 
the former to one of the latter, is made into a paste wi ,h 
water, and then rolled between the fingers into a globu'ar 
form. In order to preserve the spongy texture of the plati- 
num, a little muriate of ammonia is mixed with the paste; 
and when the ball has become dry, it is cautiously ignited 
at the flame of a spirit-lamp. The sal-ammoniac, escaping 
from all parts of the mass, gives a degree of porosity 
which is pecuharly favorable to its action. The ball, thus 
prepared, should be protected from dust, and be heated to 
redness just before being used. To insure accuracy, the 
hydrogen employed should be kept over mercury for a few 
hours in contact with a spongy platinum ball and a piece of 
caustic potash. The first deprives it of traces of oxygen, 
which it commonly contains, and the second of moisture and 
sulphuretted hydrogen. The analysis must be performed in 
a mercurial trough. The time required for completely remov- 
ing the oxygen depends on the diameter of the tube. If the 
mixture is contained in a very narrow tube, the diminution 
16* 



370 ANALYSIS C)K CASKS 

does not arrive at its full extent in less than twenty minutes 
or half an hour; while in a vessel of an inch in diameter 
the effect is complete in the course of five minutes. 

Mude of Determining the Quaiitity of Nitrogen in Gase- 
ous Mixtures. — As atmospheric air, which has been de- 
prived of moisture and carbonic acid, consists of oxygen 
and nitrogen only, the proportion of the latter is, of course, 
known as soon as that of the former is determined. The 
only method, indeed, by which chemists are enabled to es- 
timate the quantity of this gas, is by withdrawing the other 
gaseous substances with which the nitrogen is mixed. 

Mode of Determining the Quantity of Carbonic Acid in 
Gaseous Mixtures. — When carbonic acid is the only acid 
gas which is present, as happens in atmospheric air, in the 
ultimate analysis of organic compounds, and in most other 
analogous researches, the process for determining the quan- 
tity of carbonic acid is exceedingly simple ; for it consists 
merely in absorbing that gas by lime water, or a solution 
of caustic potash. This is easily done, in the course of a 
few minutes, in an ordinary graduated tube ; or it may be 
effected, almost instantaneously, by agitating the gaseous 
mixture with the alkahne solution, in Hope's eudiometer. 
This apparatus is formed of two parts ; a bottle capable of 
containing about twenty drachms of fluid, and furnished 
with a well-ground stopper ; and a tube of the capacity of 
one cubic inch, divided into 100 equal parts, and accurately 
fitted, by grinding, to the neck of the bottle. The tube, 
ftill of gas, is fixed into the bottle previously filled with hme 
water, and its contents are briskly agitated. The stopper 
is then withdrawn under water, when a portion of liquid 
rushes into the tube, supplying the place of the gas which 
has disappeared ; and the process is afterwards repeated, as 
long as any absorption ensues. 

The eudiometer of Dr. Hope was originally designed for 
analyzing air or other similar mixtures, the bottle being 
filled with a solution of the hydro-sulphuret of potassa, or 
lime, or some liquid capable of absorbing oxygen. To the 
employment of this apparatus it has been objected, that the 
absorption is rendered slow by the partial vacuum which is 
continually taking place within it, an inconvenience par- 
ticularly felt towards the close of the process, in consequence 
of the eudiometric liquor being diluted by the admission of 
water. To remedy this defect. Dr. Henry has substituted 
a bottle of elastic gum for that of glass, by which contri- 



ANALYSIS OF MINERALS. 37 j 

vance no vacuum can occur. From the improved method 
of analj'zing air, however, this instrument is now rarely em- 
ployed in eudiometrj ; but it may be used with advantage 
for absorbing carbonic acid of similar gases, and is particu- 
larly useful for the purpose of demonstration. 

Mode of Anal 1/ zing 7nixtures of Hydrogen and other inflam- 
mahle gases. — When hydrogen is mixed with nitrogen, air, 
or other similar gaseous mixtures, its quantity is easily as- 
certained by causing it to combine with oxygen, either by 
means of platinum sponge, or the electric spark. If, instead 
of hydrogen, any other combustible substance, such as car- 
bonic oxide, light carburetted hydrogen, or olefiant gas, is 
mixed with nitrogen, the analysis is easily effected by ad- 
ding a sufficient quantity of oxygen, and detonating the 
mixture by electricity. The diminution in volume indicates 
the quantity of hydrogen contained in the gas, and from the 
carbonic acid, which may then be removed by an alkali, 
the quantity of carbon is inferred. 

When olefiant gas is mixed with other inflammable gases, 
its quantity is easily determined by an elegant and simple 
process proposed by Dr. Henry. It consists in mixing 100 
measures, or any convenient quantity of the gaseous mixture, 
with an equal volume of chlorine, in a vessel covered with a 
piece of cloth, or paper, so as to protect it from light ; and 
after an interval of about ten minutes, the excess of chlorine 
is removed by lime water, or potassa. The loss experienced 
by the gas to be analyzed, indicates the exact quantity of 
olefiant gas which it had contained. 

In mixtures of hydrogen, carburetted hydrogen, and car 
bonic oxide, the analytic process is exceedingly difficult and 
complicated, and requires all the resources of the most re- 
fined chemical knowledge, and all the address of an expe- 
rienced analyst. The most recent information on this subject 
will be found in Dr. Henry's Essay, in the Philosophic?il 
Transactions for 1824. 

ANALYSIS OF MINERALS. 

As the very extensive nature of this department of analy- 
tical chemistry renders a selection necessary, I shall confine 
my remarks solely to the analysis of those earthy minerals 
with which the beginner usually commences his labors. 
The most common constituents of these compounds are si- 
lica, alumina, iron, manganese, lime, magnesia, potassa, 
soda, and the carbonic and sulphuric acids ; and I shall, 



372 ANALYSIS OF MINERALS. 

therefore, endeavor to give short directions for determining 
ihb quantity of each of these substances. 

In attempting to separate two or more fixed principles from 
each other, the first object of the analytical chemist is lO 
bring them into a state of solution. If they are soluble in 
water, this fluid is preferred to every other menstruum, but 
if not, an acid, or any convenient solvent may be employed. 
In many instances, however, the substance to be analyzed 
resists the action even of the acids, and in that case, the fol- 
lowing method is adopted : — The compound is first crushed 
by means of a hammer, or a steel mortar, and is afterwards 
reduced to an impalpable powder in a mortar of agate ; it is 
then intimately mixed with three, four, or more times its 
weight of potassa, soda, baryta, or their carbonates ; and 
lastly, the mixture is exposed in a crucible of silver, or pla- 
tinum, to a strong heat. During the operation, the alkali 
combines with one or more of the constituents of the mineral; 
and, consequently, its elements being disunited, it no longer 
resists the action of the acids. 

Analysis of Marble or Carbonate of Lime. — This analj^^sis 
is easily made by exposing a known quantity of marble, for 
about half an hour, to a full white heat, by which means 
the carbonic acid gas is entirely expelled, so that by the loss 
in weight the quantity of each ingredient, supposing the 
marble to have been pure, is at once determined. In order 
to ascertain that the whole loss is owing to the escape of 
carbonic acid, the quality of this gas may be determined by 
a comparative analysis. Into a smiall flask, containing 
muriatic acid, diluted with two or three parts of water, a 
known quantity of marble is gradually added, the flask 
being inclined to one side in order to prevent the fluid from 
being flung out of the vessel during the effervescence. The 
diminution in weight experienced by the flask and its con- 
tents, indicates the quantity of carbonic acid which has been 
expelled. 

Should the carbonate suffer a greater loss in the fire than 
when decomposed by an acid, it will most probably be 
found to contain water. This may be ascertained by heat- 
ing a piece of it to redness, in a glass tube, the sides of 
which will be bedewed with moisture, if water is present. 
Its quantity may be determined by causing the watery va- 
por to pass through a weighed tube filled with fragments of 
the chloride of calcium, (muriate of lime,) by which the 
moisture is absorbed. 



ANALYSIS OF MINERALS. 373 

* Separation of Lime and Magnesia. — The more common 
kinds of carbonate of lime frequently contain traces of sili- 
cious and aluminous earths, in consequence of which, they 
are not completelj?- dissolved in dilute muriatic acid. A very 
frequent source of impurity is the carbonate of magnesia, 
which is often present in such quantity that it forms a pecu- 
liar compound called magnesian limestone. The analysis of 
this substance, so far as respects carbonic acid, is the same 
as that of marble. The separation of the two earths may 
be conveniently effected in the following manner : The so- 
lution of the mineral in muriatic acid is evaporated to per- 
fect dryness, in a flat dish, or capsule of porcelain, and after 
re-dissolving the residuum, in a moderate quantity of dis- 
tilled water, a solution of the oxalate of ammonia is added 
as long as a precipitate ensues. The oxalate of lime is then 
allowed to subside, collected on a filter, converted into quick- 
\mQ by a white heat, and weighed ; or the oxalate may be 
decomposed by a red heat, the carbonate resolved into the 
sulphate of lime by sulphuric acid, and the excess of acid 
expelled by a temperature of ignition. To the filtered liquid 
containing the magnesia, an excess of carbonate of ammo- 
nia, and then phosphate of soda is added, when the mag 
nesia, in the form of the ammoniaco-phosphate, is precipitated 
Of this precipitate, heated to redness, 100 parts correspond 
to 40 of pure magnesia. {Murray.) 

Earthy Sulphates. — The most abundant of the earthy sul- 
phates, is that of lime. The analysis of this compound is 
easily effected. By boiling it for fifteen or twenty minutes 
with a solution of twice its weight of the carbonate of soda, 
double decomposition ensues; and the carbonate of lime, 
after being collected on a filter and washed with hot water, 
is either heated to low redness, to expel the water, and 
weighed, or at once reduced to quicklime by a white heat. 
Of the dry carbonate, fifty parts correspond to twenty-eight 
of lim.e. The alkaline solution is acidulated with muriatic 
acid, and the sulphuric acid thrown dov/n by the muriate of 
baryta. From the sulphate of this earth, collected and dried 
at a red heat, the quantity of acid may easily be estimated. 

The method of analyzing the sulphates of strontia and 
baryta is somewhat different. As these salts are difficult of 
decomposition in the moist way, the following process is 
adopted : The sulphate, in fine powder, is mixed with three 
times its weight of the carbonate of soda, and the mixture 
is heated to redness in a platina crucible, for the space of 



374 ANALYSIS OF MCxERALS. 

lialf an hour. The ignited mass is then digested in hot 
water, and the insoluble earthy carbonate collected on a 
filter. The other parts of the process are the same as the 
foregoing. 

Mode of Analyzing compounds of Silica, Alumina, and Iron. 
— Minerals, thus constituted, are decomposed by an alka- 
Hne carbonate, potash, or soda, at a red heat, in the same 
manner as the sulphate of baryta. The mixture is after- 
wards digested in dilute muriatic acid, by which means all 
the ingredients of the mineral, if the decomposition is com- 
plete, are dissolved. The solution is next evaporated to dry- 
ness, the heat being carefully regulated towards the close 
of the process, in order to prevent any of the chloride of iron, 
the volatility of which is considerable, from being dissipated 
in vapor. By this operation, the silica, though previously 
held in solution by the acid, is entirel}' deprived of its solu- 
bility ; so that on digesting the dry mass in water, acidulated 
with muriatic acid, the alumina and iron are taken up, and 
the sihca is left in a state of purity. The sihceous earth, 
after subsiding, is collected on a filter, carefully edulcorated, 
heated to redness, and weighed. 

To the clear liquid containing iron and alumina, a con- 
siderable excess of a solution of pure potassa is added ; so 
as not onl}^ to throw down these oxides, but to dissolve the 
alumina. The peroxide of iron is then collected on a filter, 
edulcorated carefullj^ until the washings cease to have an 
alkaline re-action, and is well dried on a sand bath. Of 
this hydrated peroxide, forty-nine parts contain forty of the 
anhj^drous peroxide of iron. But the most accurate mode 
of determining its quantity is by expelling the water by a 
red heat. This operation, however, should be done with 
care ; since any adhering particles of paper, or other com- 
bustible matter, would bring the iron into the state of black 
oxide, a change which is known to have occurred by the 
iron being attracted by a magnet. 

To procure the alumina, the liquid in which it is dissolved 
is boiled \\'ith sal-ammoniac, when the muriatic acid unites 
with the potassa, the volatile alkali is dissipated in vapor, 
and the alumina subsides. As soon as the solution is thus 
rendered neutral, the hydrous alumina is collected on a filter, 
dried by exposure to a white heat, and quickly weighed 
after removal from the ^re. 

Separation of Iron and Manganese. — A compound of these 
metals, or their oxide, may be dissolved in muriatic acid. If 



ANALYSIS OF MINERALS. 375 

the iron is in a large proportion, compared with the manga- 
nese, the following process may be adopted with advantage : 
To the cold solution, considerably diluted with water, and 
acidulated with muriatic acid, carbonate of soda is gradually 
added, and the liquid is briskly stirred with a glass rod, 
during the effervescence, in order that it may become highly 
charged with carbonic acid. By neutralizing the solution 
in this manner, it at length attains a point at which the per- 
oxide of iron is entirely deposited, leaving the liquid color- 
less ; while the manganese, by aid of the free carbonic acid, 
is kept in solution. The iron, after subsiding, is collected 
on a filter, and its quantity determined in the usual manner. 
The filtered hquid is then boiled with an excess of the car- 
bonate of soda ; and the precipitated carbonate of manga- 
nese is collected, heated to low redness in an open crucible, 
by which it is converted into the brown oxide, and weighed. 
This method is one of some dehcacy ; but in skillful hands, 
it affords a very accurate result. It may also be employed 
for separating iron from magnesia and lime as well as from 
manganese. 

But if the proportion of iron is small, compared with that 
of manganese, the best mode of separating it is by the suc- 
cinate of ammonia or soda, prepared by neutralizing a solu 
tion of succinc acid with either of those alkalies. That this 
process should succeed, it is necessary that the iron be 
wholly in the state of peroxide, that the solution be exactly 
neutral, which may easily be insured by the cautious use 
of ammonia, and that the reddish-brown colored succinate 
of iron be washed with cold water. Of this succinate, well 
dried at a temperature of 212° F., 90 parts correspond to 40 
of the peroxide. From the filtered liquid, the manganese 
may be precipitated at a boiling temperature by carbonate ol 
soda, and its quantity determined in the way above men- 
tioned. The benzoate may be substituted for the succinate 
of ammonia in the preceding process. 

It may be stated as a general rule, that whenever it is in- 
tended to precipitate iron by means of the alkalies, the 
succinates, or benzoates, it is essential that this metal be in 
the maximum of oxidation. It is easily brought into this 
state by digestion with a little nitric acid. 

Separation of Manganese from Lime and Magnesia. — If 
the quantity of the former be proportionally small, it is pre- 
cipitated as a sulphuret by the hydrosulphuret of ammonia 
or potassa. This sulphuret is then dissolved in muriatic 



376 ANALYSIS OF MINERALS. 

acid, and the manganese thrown down as usual bj mear-i 
of an alkah. But if the manganese be the chief ingredient^ 
the best method is to precipitate it at once, together with the 
two earths, bj a fixed alkahne carbonate, at a boihng tempe- 
rature. The precipitate, after being exposed to a low red heat 
and weighed, is put into cold water, acidulated with a drop 
or two of nitric acid, when the hme and magnesia will be 
slowly dissolved with effervescence. Should a trace of the 
manganese be likewise taken up, it may easily be thrown 
down by the hydrosulphuret of ammonia. 

Mode of Analysing an Earthy Mineral containing Silica, 
Iron, Alumina, Manganese, Lime and Magnesia. — The min- 
eral, reduced to a fine powder, is ignited with three or four 
times its weight of the carbonate of potassa or soda, the 
mass is taken up in dilute muriatic acid, and the silica sep- 
arated in the way already described. To the solution, thus 
freed from silica and dul}^ acidulated, carbonate of soda is 
gradually added, so as to charge the liquid with carbonic 
acid, as in the analysis of iron and manganese. In this 
manner the iron and alumina are alone precipitated, substan- 
ces w^hich may be separated from each other by means of 
pure potassa. The manganese, lime, and magnesia, may be 
determined by the processes already described. 

Analysis of Minerals Containing a Fixed Alkali. — When 
the object is to determine the quantity of a fixed alkali, such 
as potassa or soda, it is necessarj' to abstain from the employ- 
ment of these re-agents in the analj^sis itself; and the begin- 
ner will do well to devote his attention to the alkaline 
ingredients only. On this supposition, he wnll proceed in 
the following manner. The mineral is reduced to a very 
fine powder, mixed intimately with six times its weight of 
the artificial carbonate of baryta, and exposed for an hour to 
a white heat. The ignited mass is dissolved in dilute muri- 
atic acid, and the solution evaporated to perfect dryness. 
The soluble parts are taken up in hot water: an excess of 
the carbonate of ammonia is added ; and the insoluble mat- 
ters, consisting of silica, carbonate of baryta, and all the 
constituents of the mineral, excepting the fixed alkali, 
are collected on a filter. The clear solution is evaporated 
to dryness in a porcelain capsule, and the-dry mass is heated 
to redness in a ci-ucible of platinum, in order to expel the 
salts of ammonia. The residue is the chloride of potassium 
or sodium. 

In this analysis, it generally happens that traces of man- 



ANALYSIS OF MINERALS. 377 

gaiiese, and sometimes of iron, escape precipitation m the 
first part of the process ; and, in that case, thej should be 
thrown down bj the hydrosulphm-et of ammonia. If neither 
hme nor magnesia is present, the akunina, iron, and manga- 
nese, may be separated by pure ammonia, and the baryta 
subsequently removed by the carbonate of that alkali. By 
this method the carbonate of baryta is recovered in a pure 
state, and may be reserved for another analysis. The baryta 
may also be thrown down, as a sulphate, by sulphuric acid, 
in which case, the soda or potassa is procured in combina- 
tion with that acid. 

The analysis is attended with considerable inconvenience, 
when magnesia happens to be present, because this earth is 
not completely precipitated, either by ammonia or its carbo- 
nate ; and, therefore, some of it remains with the fixed alkali. 
The best mode with which I am acquainted for effecting its 
separation, is the following: The carbonate of ammonia is 
fi.rst added, and the phosphoric acid is dropped into the 
hquid, until all the magnesia is thrown down in the form of 
the ammoniaco-magnesian phosphate. The excess of phos- 
phoric acid is afterwards removed by the acetate of lead, 
and that of lead by sulphuretted hydrogen. The acetate 
of the alkali is then brought to dryness, ignited, and by the 
addition of sulphate of ammonia is converted into a sulphate. 

In the preceding account, several operations have been 
alluded to, which, from their importance, deserve more par- 
ticular mention. The process of filtering, for example, is 
one on which the success of analysis materially depends. 
Filtration is effected by means of a glass funnel, into which 
a filter, made of white bibulous paper, is inserted. For 
researches of delicacy, the filter, before being used, is mac- 
erated for a day or two in water, acidulated with nitric acid, 
in order to dissolve lime and other substances contained 
in common paper, and it is afterwards washed with hot 
water, till every trace of acid is removed. It is next dried 
at 212°, or any fixed temperature insufficient to decompose 
it, and then carefully weighed, the weight being marked 
upon it with a pencil. As dry paper absorbs hygrometic 
moisture rapidly from the atmosphere, the filter, while being 
weighed, should be inclosed in a light box made for the pur- 
pose. When a precipitate is collected on a filter, it is washed 
with pure water until every trace of the original hquid is 
removed. It is subsequently dried and weighed as before, 
and the weight of the paper subtracted from the coii>bined 



378 ANALYSIS OF MINERAL WATERS. 

weight of the filter and precipitate. The trouble of weigh 
ing the filter may sometimes be dispensed with. Some sub' 
sta!ices, such as sihca, alumina, and lime, which are not 
decomposed when heated with combustible matter, may be 
put into a crucible while jet contained in the filter, the paper 
being set on fire before it is placed in the furnace. In these 
instances, the ash from the paper, the average weight of 
which is determined by previous experiments, must be sub- 
tracted from the weight of the heated mass. 

The tests commonly employed in ascertaining the acidity 
or alkalinity of liquids are litmus and turmeric paper. The 
former is made by digesting litmus, reduced to a fine powder, 
in a small quantity of water, and painting with it white 
paper which is free from alum. The turmeric paper is made 
in a similar manner ; but the most convenient test of alka- 
linity is litmus paper reddened by a dilute acid. 

ANALYSIS OF MINERAL WATERS. 

Rain water, collected in clean vessels in the country, or 
freshly fallen snow, when melted, affords the purest kind of 
water which can be procured without having recourse to 
distillation. The water obtained from these sources, how- 
ever, is not absolutely pure, but contains a portion of car- 
bonic acid and air, absorbed from the atmosphere. It is 
remarkable that this air is very rich in oxygen. That pro- 
cured from snow-water by boiling, was found by Gay Lus- 
sac and Humboldt to contain 34.8 and that from rain water 
32 per cent, of oxygen gas. From the powerfully solvent 
properties of water, this fluid no sooner reaches the ground 
and percolates through the soil, than it dissolves some of 
the substances which it meets with in its passage. Under 
comm.on circumstances, it takes up so small a portion of 
foreign matter that its sensible properties are not materially 
affected, and in this state it gives rise to springy well^ and 
river water. Sometimes, on the contrary, it becomes so 
strongly impregnated with saline and other substances, that 
it acquires a peculiar flavor, and is thus rendered unfit for 
domestic uses. It is then known by the name of mineral 
water. 

The composition of spring water is dependent on the 
nature of the soil through which it flows. If it has filtered 
through primitive strata, such as quartz rock, granite, and 
the like, it is in general very pure ; but if it meets with 
limestone or gypsum in its passage, a portion of these salts 



A.NALVS1S OF MINERAL WATERS. 379 

is dissolved, and communicates the property called hardness 
Hard water is characterized by decomposing soap, the lime 
of the former yielding an insoluble compound with the 
oil of the latter. If this defect is owing to the presence of 
the carbonate of lime, it is easily remedied by boilmg, when 
free carbonic acid is expelled, and the insoluble carbonate of 
hme subsides. If sulphate of lime is present, the addition 
of a httle carbonate of soda, by precipitating the lime, con- 
verts the hard into soft water. Besides these ingredients, 
the muriates of lime and soda are frequently contained m 
spring water. . 

Spring water, in consequence of its saline impregnation, 
is frequeiitly unfit for chemical purposes, and on these oc- 
casions distilled water is employed. Distillation may be 
performed on a small scale by means of a retort, in the body 
of which water is made to boil, while the condensed vapor 
is received in a glass flask, called a recipient, which is 
adapted to its beak or open extremity. This process is 
more conveniently conducted, however, by means of a still. 
The different kinds of mineral water may be conveniently 
arranged for the purpose of description in the four divisions 
of carbonated, chalybeate, sulphurous, and saline springs. 

The carbonated springs of which those of Seltzer, Spa, 
Pyrmont, Ballston and Carlsbad, are the most celebrated, are 
distino-uished by containing a considerable quantity of free 
carbonic acid, owing to the escape of which they sparkle 
when poured from one vessel into another. They commu- 
nicate a red tint to htmus paper before, but not after being 
boiled, and the redness disappears on exposure to the air. 
Mixed with a sufficient quantity of Hme water, they become 
turbid from the deposition of carbonate of lime. They fre- 
quently contain the carbonate of lime, magnesia, and iron, 
in consequence of the facility with which these salts are 
dissolved by water charged with carbonic acid. 

The best mode of determining the quantity of carbonic 
acid is by heating a portion of the water in a flask, and 
receiving the carbonic acid by means of a bent tube, in a 
graduated jar filled with mercury. 

The chalybeate waters are characterized by a strong styp- 
tic inky taste, and by striking a black color with the infu- 
sion of gallnuts. The iron is sometimes combined with the 
muriatic or sulphuric acid ; but most frequently it is ni the 
form of a carbonate of the protoxide, held in a solution by 
free carbonic acid. On exposure to the air, the protoxide is 



380 ANALYSIS OF MINERAL WATERS. 

oxidized, and the hjdrated peroxide subsides, causing the 
ocjireous deposit, so commonly observed in the vicinity of 
chalybeate springs. 

To ascertain the quantity of iron contained in a mineral 
water, a known weight of it is concentrated by evaporation, 
and the iron brought to the state of peroxide by means of 
nitric acid. The peroxide is then precipitated by an alkali 
and weighed ; and if lime and magnesia are present, it may 
be separated from those earths by the process described in 
the last section. 

Chalybeate waters are by no means uncommon ; but the 
most noted in Britain are those of Tunbridge, Cheltenham, 
and Brighton. The Bath water also contains a small quan- 
tity of iron. 

The sulphurous waters, of which the springs of Aix la 
Chapelle, Harrowgate, and Moffat afford examples, contain 
sulphuretted hydrogen, and are easily recognized by their 
odor, and by causing a brown precipitate with a salt of lead 
or silver. The gas is readily expelled by boiling, and its 
quantity may be inferred by transmitting it through a solu- 
tion of the acetate of lead, and weighing the sulphuret which 
is generated. 

Those mineral springs are called saline which do not 
belong to either of the preceding divisions. The salts which 
are most frequently contained in these waters, are the sul- 
phates, muriates, and carbonates of lime, magnesia, and 
soda. Potassa sometimes exists in them, and Berzelius 
has found lithia in the spring at Carlsbad. It has lately 
been discovered that the presence of hydriodic acid in small 
quantity is not infrequent. As examples of saline water 
may be enumerated the springs of Epsom, Cheltenham, 
Bath, Bristol, Bareges, Buxton, Pithcaithly, Toephtz, Ball- 
ston, and Saratoga. 

The first object in examining a saline spring is to deter- 
mine the nature of its ingredients. Muriatic acid is detected 
by the nitrate of silver, and the sulphuric acid by muriate 
of baryta ; and if an alkaline carbonate be present, the pre- 
cipitate occasioned by either of these tests will contain a 
carbonate of silver or baryta. The presence of lime and 
magnesia may be discovered, the former by the oxalate of 
hme, and the latter by carbonate of ammonia and the phos- 
phoric acid. Potassa is known by the action of the muriate 
of platinum. To detect soda, the water should be evapo- 
rated to dryness, the dehquescent salts removed by alcohol^ 



AiNALYSIS OF MINERAL WATERS. 381 

and the meitter insoluble in that menstruum taken up by a 
small quantity of water, and be allowed to crystalize by 
spontaneous evaporation. The salt of soda may then be 
recognized by the rich yellow color which it communicates 
to flame. If the presence of hydriodic acid is suspected, 
the solution is brought to dryness, the soluble parts dissolved 
in two or three drachms of a cold solution of starch, and 
strong sulphuric acid gradually added. 

Having thus ascertained the nature of the saline ingre- 
dients, their quantity may be determined by evaporating a 
pint of water to dryness, heating to low redness, and weigh- 
ing the residue. In order to make an exact analysis, a 
given quantity of the mineral water is concentrated in an 
evaporating basin, as far as can be done without causing 
either precipitation or crystahzation, and the residual liquid 
is divided into two equal parts. From one portion the sul- 
phuric and carbonic acids are thrown down by the nitrate 
of baryta, and after collecting the precipitate on a filter, the 
muriatic acid is precipitated by the nitrate of silver. The 
mixed sulphate and carbonate is exposed to a low red heat, 
and weighed ; and the latter is then dissolved by dilute 
muriatic acid, and its quantity determined by weighing the 
sulphate. The chloride of silver, of which 146 parts cor- 
respond to 37 of muriatic acid, is fused in a platinum spoon 
or crucible, in order to render it ouite free from moisture. 
To the other half of the concentrated mineral water, oxalate 
of lime is added for the purpose of precipitating the lime ; 
and the magnesia is afterwards thrown down as the am- 
moniaco-phosphate, by means of the carbonate of ammonia 
and phosphoric acid. Having thus determined the weight 
of each of the fixed ingredients, excepting the soda, the loss 
of course gives the quantity of that alkali ; or it may be pro- 
cured in a separate state by the process described in the fore- 
going section. 

The individual constitutents of the water being known, it 
remains to determine the state in which they were originally 
combined. In a mineral water containing sulphuric and 
muriatic acids, lime, and soda, it is obvious that three cases 
are possible. The liquid may contain sulphate of lime and 
muriate of soda, muriate of lime and sulphate of soda, or 
each acid may be distributed between both the bases. It 
was at one time supposed that the lime must be in combina- 
tion with sulphuric acid, because the sulphate of that earth 
is left, when the water is evaporated to dryness. This, 



382 ANALYSIS OF MINERAL WATERS. 

however, by no means follows. In whatever state the lime 
may exist in the original spring, gjpsum will be generated 
as soon as the concentration reaches that degree at which 
sulphate of lime cannot be held in solution. The late Dr. 
Murray,* who treated this question with much sagacity, 
observes, that some mineral waters, which contain the four 
principles above mentioned, possess higher medicinal vir- 
tues than can be justly ascribed to the presence of sulphate 
of lime and muriate of soda. He advances the opinion, that 
alkaline bases are united in mineral waters with those acids 
with which they form the most soluble compounds, and that 
the insoluble salts obtained by evaporation are merely pro- 
ducts. He therefore proposes to arrange the substances 
determined by analysis according to this supposition. To 
this practice there is no objection ; but it is probable that 
each acid is rather distributed between several bases, than 
combined exclusively with one of them. 

Sea water may be regarded as one of the saline mineral 
waters. Its taste is disagreeably bitter and saline, and its 
fixed constituents amount to about three per cent. Its spe- 
cific gravity varies from 1.0269 to 1.0285; and it freezes at 
about 28.5° F. According to the analysis of Dr. Murray, 
10,000 parts of water from the Firth of Forth contain 220.01 
parts of common salt, 33.16 of sulphate of soda, 42.08 of 
muriate of magnesia, and 7.84 of muriate of lime. Dr. Wol- 
laston has detected potassa in sea water, and it likewise 
contains small quantities of the hydriodic and iodic and 
hydrobromic acids. 

The water of the Dead Sea has a far stronger saline im- 
pregnation than sea water, containing one-fourth of its 
weight of solid matter. It has a peculiarly bitter, saline, and 
pungent taste, and its specific gravity is 1.211. According 
to the analysis of Dr. Marcet, 100 parts of it are composed 
of muriate of magnesia, 10.246, muriate of soda, 10.36, mu- 
riate of hme, 3.92, and sulphate of lime, 0.054. In the rivei 
Jordan, which flows into the Dead Sea, Dr. Marcet dis 
covered the same principles as in the lake itself — Turner'^ 
Chemistry. 

* Philosophical Transactions of Edinburgh, vol. vii. 



CHEMICAL MINERALOGY. 383 

PART V. 

CHEMICAL MINERALOGY. 

By Chemical Mineralogy, we mean the application of the 
principles of chemistry to the examination of mineral sub- 
stances. 

In this short treatise on the subject, we shall be confined 
chiefly to the examination of the most common mineraJ 
bodies, and hope to give such plain directions as will enable 
the student to assay the most important metallic ores of oui 
country. 

Instruments and Preparatory Steps necessary for the Analy 
sis of Metallic Ores. — Before we proceed to show the methods 
by which ores are analysed, it will be necessary to describe a 
few simple instruments which are required for this purpose ; 
and also to point out what preHminary steps are necessary 
in order to prepare the ores for analysis. 

1. A Bala?ice, or pair of small scales, in order to ascertain 
the weight of the ore to be examined. Also to take the 
specific gravities of minerals. The latter may be done 
by the method and instrument described at p. 121 of this 
volume. 

2. Blow-pipe. — For a description of this, and the manner 
of using it, see p. 115. 

3. Supports. — In order to use the blow-pipe, it is neces- 
sary to employ a support, on which the substance to be 
heated rests. In ordinary cases, a piece of charcoal an- 
swers for this purpose, but in others it is necessary to use 
a small platina spoon, or piece of platina foil, instead of the 
charcoal. 

4. Magnet. — This is used in order to ascertain whether 
the ore contains metahic iron. The best form is that of a 
small needle suspended on a fine point of copper, or brass. 
The ore should be tried both before and after being heated 
by the blow-pipe ; because^ although the ore may contain 
iron, it may not be magnetic until it is reduced. 

5. Mortar and Pestle. — A common v/edgewood mortar is 
sufficient for most purposes. All substances to be analysed 
must be levigated as finely as possible. In most mstances. 
the action of the solvents will be incomplete without this 
preparation. 



384 CHEMICAL MINERALOGY. 

6. A Flask for digesting- the ore after levigation is neces- 
sarj. This has aheady been described at p. 115. 

7. Test Tubes. — These are of glass, five or six inches 
long, and of various sizes. Thej may be made by taking 
pieces of glass tube, already broken, and closing them at one 
end by means of the blow-pipe, or alcohol lamp. They are 
employed to subject small portions of the clear filtered solu- 
tion of any substance to the action of various tests, and are 
among the vn^dispensable instruments of analysis. 

8. Glass Plates. — In many instances, when the quantity 
of matter is small, a drop in solution, placed on a glass 
plate, and tnen the test applied by means of a point of glass, 
or piece of platina wire, will decide all the operator wishes 
to know before he proceeds to further trials. Where the 
solution contains neutral, or other salts, by allowing the drop 
to dry we may decide what the solution is, by the forms of 
the crystals on the glass. {For Crystaline Forms, see the 
Author'' s Mineralogy. ) 

PROCESSES NECESSARY BEFORE THE CHEMICAL 
EXAMINATION OF METALLIC SUBSTANCES. 

Roasting. — This consists in keeping the ore at a moderate 
heat for a considerable length of time, in order to drive off 
all the volatile matter it contains, as water, carbonic acid, 
sulphur, &c. Roasting, in the large way, is performed by 
placing alternate layers of the ore, and wood, or coal, in a 
chimney erected for this purpose, and then setting the fuel 
on fire at the bottom of the pile. Some ores consume days, 
or weeks, in this process. In the small way, what is called 
a muffle^ or a common crucible, will answer all purposes, 
first breaking the ore into small fragments. A dull red heat 
is a sufficient temperature for most ores. 

Reduction. — That is, reducing the ore to its metallic state, 
is generally performed in the small way by means of pow- 
dered charcoal, or black flux, in a crucible, or black lead 
pot. Where the compound is the oxide of a metal, the char- 
coal, at a high degree of heat, absorbs the oxyge.i from it, 
and thus the metal is revived, or reduced to its pure metallic 
form. For this purpose, the ore, as well as the charcoal, 
must be in powder, and mixed together, and the heat, in 
most cases, raided to whiteness. 

Cupellation. — This process is apphcable only to gold and 
silver. When either of these metals are in an impure state, 
they are further alloyed with two or three times their weight 




CHEMICAL MINERALOGY'. §85 

of lead, by melting them together. This mass is then placed 
in ci kind of dish made of bone ashes, and in this state su> 
jected to a sufficient heat to melt it, when the lead, togethor 
with the impurities, sink down into the cupel, and thus leave 
the gold or silver pure in the dish. 

Muffle. — This is a small pot of clay arched over the to ) 
in the form of an oven, the upper part of which has severa 1 
apertures near the bottom, «, to 
admit the air. Fig. 82. In this 
the cupel is placed bj the door, Z>, 
before the heat is applied. The 
muffle is then surrounded with 
coal, and the heat raised to white- 
ness. The use of the muffle is to 
protect the contents of the cupel from the contact of the coal, 
and other impurities. 

Fluxing. — This process is necessary when the ore con- 
tains any considerable quantity of silicious, or stony matter. 
The chemical action concerned in the process, consists in 
the union of the silicious matter of the ore with the flux 
employed. As an example, mix together a given quantity 
of lead, or iron ore, with four times its weight of caustic 
potash, the ore being pulverized, and put the mass into a 
crucible of silver, and having put on the cover, subject it to 
a low red heat for half an hour Then remove the crucible 
and pour in water, which will dissolve the potash which 
has combined with the silex. The water being carefully 
decanted, and the process repeated with hot water, the silex 
and other earthy matters will be washed away, and the 
metal left in the crucible. In most instances, it is neces- 
sary to grind the m iss in a mortar, and wash it through a 
filter before the pctash and metal are entirely separated. 
The ore which remains on the filter then becomes in a state 
to be dissolved in an acid, and is to be treated according to 
circumstances. 

Fusion. — This is the conversion of solids into fluids by 
heat. It is usually called melting. Fusion is eflected in 
diflerent ways, according to the kind of ore to be acted upon, 
or its quantity. Minute fragments are melted by the blow- 
pipe, while for larger quantities the crucible, and forge or 
furnace, are employed. Many substances which are infu- 
sible alone, readily enter into fusion when surrounded with 
another substance which acts upon it chemically, or which 
merely serves to retain the heat. 
17 



566 ANALYSIS OF METALLIC SUBSTANCES. 

In making experiments on ores with the blow-pipe, the 
glass of borax is commonly emploj^ed. This is the common 
borate of soda, previously exposed to such a degree of heat 
as to drive off the water of crystalization. What is termed 
the hlack flux is also much employed to assist in melting 
refractory bodies. This is made by mixing two parts of the 
cream of tartar with one part of nitre, and deflagrating the 
mixture in a ladle, or other vessel. 

When the ores of metals are fused in a crucible, the 
pure metal is found at the bottom, in the form of a button, 

Elutriation. — By this term is meant the repeated washing 
of any substance, as a precipitate, in order to free it from 
any remains of its solvent. 

In the analysis of ores, these washings must, in certain 
cases, be retained, and added to the filtered solution. When 
this is important, it will be mentioned when the description 
of the analysis is given. 

Evaporation. — This is a process by which the fluid, or 
volatile parts of a solution are separated from those which 
are solid. In some instances heat is employed for this pur- 
pose, while in others the process is suffered to go on by the 
natural action of the atmosphere. 

When the object is merely to find the weight of the solid 
portion of the mixture, or compound, a gentle heat facili- 
tates the process, but when we wish to obtain fine crystals 
from a saline solution, the action of the atmosphere only is 
much the best. In either case, shallow dishes of porcelain, 
or wedgewood ware, called evapoi^ating dishes, are com- 
monly used, though common white earthen ware dishes 
answer most purposes. 

ANALYSIS OF METALLIC SLBSTANCES. 

The tests, and re-agents required for the analysis of each 
metallic body, will be mentioned in connection mth their 
uses, and in describing the several processes by which each 
metal, or its alloy, is to be detected. 



This metal is always found in the reguline, or native 
state, but is seldom or never found perfectly pure, being 
alloyed with various metals, but most commonly with silver 
and copper. 



ANALYSIS OF MEl^ALLIC SUBSTANCES. 387 



TESTS FOR GOLD. 

Proto-sulphate of Iron gives Metallic Gold. 

Recent muriate of Tin " Purple precipitate. 

Potash and Soda " Yellow do. 

Hydro-sulphurets " Black do. 

Tests, or re-agents, are substances generally in the liquid 
form, by which certain other substances are indicated by 
the color, or appearance of the precipitates which the mu- 
tual action of the two bodies produce. Thus, a solution of 
iron is instantly turned black by an infusion of nut galls. 
This infusion is, therefore, a test for the presence of iron in 
solution, and the muriate of tin is a test for gold, by throw- 
ing down a purple precipitate, and so of the other re-agents. 



Assay, or trial, is the means by which the quantity of 
precious or valuble metals is found to exfet in a small 
quantity of ore, or alloyed metal. The practical difference 
between the assay and the analysis of an ore, consists in this : 
The analysis determines the nature and quantity of all the 
substances which the ore, or metaUic mixture contains; 
whereas the object of the assay is to find how much of the 
particular metal in question is contained in a given quantity 
of the compound under examination. Thus, in the assay 
of gold, or silver, the baser metals they contain are consid- 
ered of no value, the object of trial on a small quantity 
being merely to find the per centage of precious metal con- 
tained in the whole, of which this is a sample. 

ASSAY OF GOLD. 

There are two or three methods by which the quantity of 
gold, dispersed through the stony matrix in which it is found, 
is determined. 

The first is, by dissolving the metal in its proper solvent, 
then by a precipitate to throw the metal down, and after- 
wards melt it in a crucible. This is called assaying in the 
moist way. 

The other is, to melt the gold with lead, in a cupel, when 
the lead, combining with the other metals the gold con- 
tained, sinks into the substance of the cupel, leaving the 
gold on the surface. This is called assaying in the dry way, 
or by cupellation. Gold dust is assayed by this method. 
The last method is by amalgamation with quicksilver, and 



388 ANALYSIS OF METALLIC SUBSTANCES. 

afterwards driving off this bj heat, and thus leaving the 
gold in a nearly pure state. 

The assay in the moist way, the only one it is necessary 
here to describe, is extremely simple, and easily performed 

Take a certain quantity of the stony matter containing 
the gold, say 400 grains, and having reduced it to a fine 
powder, mix it intimately with four times its weight of dry 
caustic potash, to \Mhich a little borax may be added. 
Place this mixture in a crucible, (this should be of silver,) 
and expose it to a dull red heat for an hour. In most cases, 
at the end of this time, the metal will have melted, and run 
into the bottom of the crucible. 

Sometimes, however, from the imperfect fusion of the 
mass, or the small quantity of metal it contains, the metal 
is found in globules dispersed in it, and not united in a 
button at the bottom. In this case, the whole mass, cruci- 
ble and all, may be placed in an iron vessel and boiled, un- 
til the flux is entirely dissolved, and thrown away. The 
small globules, together with the other matter which the 
water did not dissolve, may now be digested with eight or 
ten times its weight of nitro-muriatic acid, in a moderate 
heat, until the whole is dissolved, and all action has ceased. 
Then pour off the clear liquor, elutriate any residue that 
may remain, with warm water, and add the washings to 
the first solution. 

The gold is now in solution ^vith dilute nitro-muriatic 
acid, and must be precipitated by means of a solution of 
proto-sulphate of iron, which is to be added until no more 
precipitate falls. The whole is next to be thrown on a fil- 
ter, elutriated, and the moisture suffered to pass, while that 
which remains is to be mixed with half its weight of nitre, 
and a little borax, and melted in a crucible as before, when 
a button of pure gold will be found at the bottom. 

ANALYSIS OF NATIVE GOLD. 

Native gold, or gold as it occurs in its natural state, is 
usually alloyed with various proportions of metallic silver, 
and copper. The proportions of each are found by the 
following method : 

Process 1. — Digest a given quantity of the metal, say 
100 grains, with so much nitro-muriatic acid as to dissolve 
the whole. During this process, a white flocculent precip- 
itate will fall to the bottom of the vessel, which is the sil- 
ver in the form of a chloride of that metal. The clear 



ANALYSIS OF METALLIC SUBSTANCES. 889 

liquor must be decanted, leaving this to be collected, 
washed, and dried on a filter, and then weighed. The pro 
portion of pure silver may be estimated at three quarters 
the weight of the chloride. 

Process '2. — The remaining solution to which the wash- 
ings of the precipitated silver was added, contains the solu- 
tions of gold and copper. On adding a solution of the 
proto-sulphate of iron, the gold will be precipitated, when 
the clear liquor must be decanted, and the precipitate 
washed and dried, and afterwards reduced to the metallic 
state, by fusion with potash and borax, as above directed. 

Process 3. — The liquor now remaining contains the cop- 
per, and the little iron which was added for the separation 
of the gold. Of the iron no account is to be taken, but 
the copper is to be precipitated by inserting in the Hquor 
clean plates of iron, and heating the solution, when the 
plates will be covered with metallic copper, the weight of 
which may be ascertained by first weighing the plates, and 
then finding how much they have gained. If any of the 
copper falls to the bottom of the vessel, this must, after 
washing and drying, be added to that on the plates. 

The weight of each metal thus obtained, will, of course, 
show the proportions in the mass. 

SIL VEK. 

The ores of this metal are considerably numerous, and 
are found in greater or less quantities in nearly every coun- 
try. The most important are the following : 

Native Silver, composed of Silver and a Uttle Antimony. 
Auriferous Silver, — Silver and Gold. 
Sulphuretted Silver, — Silver and Sulphur. 
Red Silver, — Silver, Sulphur, Antimony and Oxygen. 
White Silver, — Silver, Sulphur, Antimony and Lead. 
Bismuthic Silver, — Silver, Sulphur, Bismuth and Lead. 
Carbonate of Silver, — Silver, Carbonic Acid and Antimony. 
Muriate of Silver, — Silver and Muriatic Acid. 

TESTS FOR SILVER. 

Alkalies give Dark olive precipitate. 

Plate of Copper " Metallic silver. 

Muriatic Acid, > ^^ White precipitate, which is 

and salts of, \ soluble in ammonia. 

Tincture of Galls. " Brown precipitate. 



390 ANALYSIS OF METALLIC SUBSTANCES. 

The solution of silver gives a permanent black stain to 
the skin and hair, and also to cloth and silk. Indehble 
ink for marking is a solution of nitrate of silver. 

ASSAY OF SILVER. 

The proper solvent of silver is nitric acid, and for the 
purpose in question it should be quite pure. This metal is 
not acted upon bj the fixed alkalies. 

To ascertain its puritj, the ore must be first roasted, to 
drive off any sulphur, or arsenic it may contain. It is then 
levigated, and mixed with three or four times its weight of 
caustic potash, and the whole fused in a'crucible, when the 
metal will be found at the bottom. If the metal thus ob- 
tained is found to be impure, it must be mixed with lead, 
and subjected to the process of cupellation in the manner 
directed for gold. Or, it may be assayed in the moist way, 
by dissolving it in pure nitric acid, precipitated with com- 
mon salt, the precipitate collected, dried, and mixed with 
carbonate of potash, and fused ; the button of metal thus 
obtained, will be pure silver, and its weight compared with 
that of the ore, will give the per centage. 

ANALYSIS OF SILVER ORES. 

To give the analysis of all the silver ores, would be in- 
compatible with the object of this work. An example or 
two must therefore suffice. 

AURIFEROUS SILVER. 

Process 1. — 100 grains of crystalized auriferous silver^ 
which, upon trial, was found to contain only gold, silver, 
and copper, were put into a flask with two ounces of nitro- 
muriatic acid, and heat applied. Nitrous gas in red fumes 
was disengaged, and a white curd floated in the solution, 
in consequence of the precipitating effects of the muriatic 
acid on the dissolved silver. When cold, the whole was 
thrown upon a filter, and what remained after washing 
was dried ; this being chloride of silver, was afterwards 
reduced to the metaUic state, with a little black flux, in a 
ciTicible 

Process 2. — The washings of the silver being added to the 
filtered hquor, a solution of proto-sulphate of iron was 
poured in, until no further precipitation followed. By this 
the gold was thrown down in the metallic form, which was 



ANALYSIS OF METALLIC SUBSTANCES. 39 1 

afterwards washed, dried, and reduced to a button, hy means 
of nitre, and weig-hed. 

Process 3. — Having thus obtained the gold and silver, 
the washings of the last process were added to the solution, 
which now contained the copper only. This was precipita- 
.ed by a clean plate of iron, and afterwards dried and 
.veighed. The number of grains each metal weighed, 
showed their proportions in the ore, and the sum of the 
whole indicated the loss of less than a grain. 

ANTIMONIAL SILVER. 

Process 1. — Of Antimonial Silver, 100 grains were pul- 
verized and digested, with ten times its weight of nitric 
acid. A portion being undissolved, was washed and dried, 
and found to be silex. 

Process 2. — The washings of the silex being added to 
the filtered solution, occasioned a turbidness, and on pour- 
ing in more water, a precipitate fell down, which was oxide 
of bismuth, contained in the ore. 

Process 3. — Muriate of Soda being now added, the 
whole of the silver was precipitated, which being washed 
and dried, amounted to three fourths of the metal examined. 

MURIATE OF SILVER. 

This is the richest of the silver ores, sometimes yielding 
75 per cent, of the metal. It is known to the miners by 
the name of horn silver. Its composition is silver and mu- 
riatic acid, with generally some foreign impurities. 

Process 1. — Mix the powdered ore with four times its 
weight of carbonate of potash, or soda, and flux in a cru- 
cible. When the fusion is complete, dissolve the mass with 
boiling water, elutriate what remains undissolved, and then 
digest it in nitric acid. This portion must be kept sepa- 
rate, and the silver it contains precipitated with muriate of 
soda, and reduced with black flux in a crucible. 

Process 2. — The alkaline liquor, or the washings of the 
fused mass containing the muriatic acid of the ore, combined 
with the soda, is to be brought to the point of saturation, 
with distilled vinegar. This will throw down the alumine, 
which this ore usually contains, in the form a white powder, 
which must be washed, dried, and weighed. 

Process 3. — The remaining solution now contains the 
muriatic acid of the ore, and probably some portion of the 
soda, in which it was fluxed. This is to be evaporated to 



392 ANALYSIS OF METALLIC SUBSTANCES. 

dryness, and the mass then digested for several days in al- 
cohol. This will take up the uncombined soda, while the 
other portion of soda will have combined with the muriatic 
acid of the ore, forming muriate of soda. The liquor is then 
to be evaporated, and the muriate of soda weighed, 58 parts 
of which are equal to 24 of muriatic acid. 

Process 4. — If the ore contains sulphuric acid, which is 
often the case, the salt remaining after the third process is 
to be dissolved in water, and tested with acetate of barytes, 
by which it will be precipitated. This acid is generally in 
very small quantities, and will hardly vary the result. 

MERCURY. 

This metal is sometimes found in the native state, but the 
source whence the greater portion is obtained, is from the 
sulphuret of mercury, or native cinnabar. 

The ores of this metal are. 

Cinnabar, composed of Mercury and Sulphur. 

Native Amalgam, — Mercury and Silver. 

Horn Mercury, — Mercury, Oxygen, Muriatic and Sul- 
phuric Acids. 

TESTS FOR MERCURY. 

The presence of this metal in solution, may be detected 
as follows : the re-agents being on the left, and their eflfects 
on the right. 

A plate of copper, Metallic mercury. 

A plate of iron. Dark powder. 

Fresh lime water. Orange precipitate. 

Ferro-prussiate of potash, White do. 

Hydro-sulphurets, Black do. 

Gallic acid, Orange yellow. 

In the large way, mercury is obtained by mixing the sul- 
phuret, or native cinnabar, with iron filings, or lime, and 
distilling the mixture in iron retorts. The sulphur of the 
mercury combines with the iron, or lime, and leaves the 
metal free, which being volatilized by the heat, is condensed 
in a cold vessel in the metallic form. 

An example of this process may be made in a glass tube, 
by means of a blow-pipe, by placing at the bottom, or sealed 
end of the tube, a piece of cinnabar, and inserting also a 
bright slip of copper. On applying the heat of the blow- 
pipe carefully to the ore, through the tube, the metal will 
sublime and attach itself to the copper. 



AJNALYSIS OF METALLIC SUBSTANCES. 393 



ANALYSIS OF THE ORES OF MERCURY. 

The analysis of these ores is simple, as they seldom con- 
tain many foreign ingredients. 

NATIVE CINNABAR. 

This ore, as we have already seen, is composed of mer- 
cury and sulphur. Its analj^sis may be thus effected : 

Process 1. — Take 100 grains of the ore, reduced to pow- 
der, and digest it with 8 or 10 times its weight of muriatic 
acid, adding now and then a few drops of nitric acid, to 
make the solution more perfect. When all action ceases, 
pour off the clear liquor, wash the residue, and dry it with a 
gentle heat. This will contain the sulphur, and such other 
matter as was insoluble in the acid. 

Process 2. — The insoluble matter, after drying, is to be 
heated in a platina crucible, or in the absence of this, in the 
bowl of a tobacco pipe, until all the sulphur is burned away, 
when, on re-weighing, the loss of weight will indicate the 
quantity of sulphur in the 100 grains. 

Process 3. — The clear liquor poured off in process 1, is 
now to be tested by placing a little in a test tube, and ad- 
ding tincture of nut-galls, when, if it contains iron, a dark 
precipitate will fall. Then insert a slip of clean iron, and if 
it contains copper, a coat of the metal will cover the shp. If 
the solution is found to contain only copper and iron, in ad- 
dition to the mercury, the whole must be evaporated to 
dryness, taking care not to employ so much heat as to de- 
compose the muriate of mercury. 

Process 4. — The dry mass obtained by the last process 
must be dissolved in pure water, which will dissolve the 
salts of mercury and copper, but will leave the iron behind 
in the state of a peroxide. 

Process 5. — Immerse into the watery solution a clean 
plate of iron, and gently heat it, when both the copper and 
mercury will fall down. This being thrown on a filter, and 
well washed, must be dried and weighed, and then exposed 
to a red heat, which will drive off the salt of mercury, leav-^ 
ing the copper behind. Then, on weighing the copper, the 
amount of the salt of mercury will be indicated, and the 
weight of the metal may be readily known, as the salt, 
which is the proto-chloride of mercury, contains 84 parts 
mercury, and 16 chlorine. 

17* 



394 ANALYSIS OF METALLIC SUBSTANCES. 



ARSENIC. 



The form under which this metal is best known, is that 
of the white oxide, which is the arsenious acid. The metal 
from this is readily obtained by mixing it with a httle black 
flux, or powdered charcoal, placing the mixture at the bot- 
tom of a thin glass tube, and applying the heat of a candle, 
or lamp. The charcoal will absorb the oxygen, and the 
metal will rise, and be condensed on the inside of the tube, 
coating it with a brilHant white metal. 

No mines are worked for the purpose of obtaining arsenic, 
a sufficient supply of its oxides being obtained in the pro- 
cess of working the cobalt mines of Saxony and Germany. 
The ores of arsenic present the following varieties : 
Native arsenic. Arsenic with iron. 

PharmacoHte, Arsenic, lime and oxygen. 

Arsenical pyrites, Arsenic, iron and sulphur. 

Orpiment, > ^^^^^^^ ^^^ ^^, j^^^_ 

Kealger, ) ^ 

White arsenic. Arsenic and oxygen. 

The presence of arsenic in any substance is readily 
known by the strong smell of garlic which it emits when 
exposed to heat. 

It will hardly be necessary to go through the processes 
of assaying, or analyzing the ores of arsenic, since the metal 
in the pure state is of no value, as it turns to an oxide by 
mere exposure to the atmosphere. 

The best methods of ascertaining the presence of this 
metal, are by the garHc odor above noticed, and the reduc- 
tion of it in a glass tube, by means of the black flux above 
described. It is said, however, that where the metal is in 
the state of an oxide, or acid, no garlic odor is emitted, the 
presence of metallic arsenic being necessary for the presence 
of this test. But if the oxide be heated in contact with 
charcoal, or any other reducing agent, the tnetal will always 
be present, as above explained. 

Still the most sure test is the reduction of the metal, 
since the garlic odor may possibly be so nearly imitated hy 
some other substances, as to occasion mistakes, a matter 
which may in some instances, as in suspicion of poisoning, 
jeopardize human life. 

In such cases, if the chemist is called on to examine the 
contents of the stomach, or a portion of the vehicle in which 



ANALYSIS OF METALLIC SUBSTANCES. 395 

it is supposed the arsenic was given, the fluid may be evapo- 
rated to dryness, and then mixed with black flux, and dis- 
tilled in a common retort, with the heat of a lamp. The 
arsenic, 'f any be in the mixture, will rise and coat the in- 
side of the neck of the retort, giving it a metalhc lustre 
nearly resembling quicksilver. A little of this detached, 
and heated on charcoal, if it emits the garlic odor, will de- 
cide the question beyond any doubt, that it is arsenic. 

COBALT. 

Most of the cobalt used in the arts comes from the Saxon 
mines, under the name of zaffree. This consists chiefly of 
silicious matter, containing a small portion of the oxide of 
the metal. 

The ores of cobalt, which are found in many countries, 
are chiefly the following : 

Cobalt pyrites, \ ^°^^'*' «rsenic sulphur, and some- 

^-^ ' ( trnies u'on and copper. 

Red cobalt, Cobalt and arsenic acid. 

Earthy cobalt. Oxide of cobalt, iron and arsenic. 

Sulphate of cobalt. Oxide of cobalt and sulphuric acid. 

TESTS OF COBALT. 

The solutions of the salts of this metal are either red, 
green, or blue, depending on the quantity of cobalt they 
contain. 

Potash and soda, Blue precipitate. 

Ferro-prussiate of potash. Green precipitate. 

Carbonates, Red precipitate. 

All the ores of cobalt, when melted with .borax, give a 
deep blue bead. This is the readiest and most certain 
method of ascertaining the presence of that metal. 

ANALYSIS OF COBALT. 

The cobalt pyrites, or arsenical cobalt, not only contains 
the two substances from which its scientific name is derived, 
but is often mixed with copper, iron, nickel, and bismuth 
also. Hence the analysis of this variety is considerably 
complicated. 

Process 1. — Mix one part of finely powdered arsenical 
cobalt, with three parts of nitre, in a crucible, and submit 
it to a red heat for one hour. A chemical interchange of 
elements will ensue, and the arseniate of potash will be tha 



396 ANALYSIS OF METALLIC SUBSTANCES. 

result. Dissolve this in nitric acid, and if any residue 
remains undissolved, mix it with nitre, and heat in a cruci- 
ble as before ; then digest in nitric acid and filter. 

Process 2. — Evaporate the nitric acid solution with heat, 
in order to drive off ?mj excess of acid, and then dilute with 
a large quantity of water. This will separate the bismuth, 
which will fall down in form of a white powder, which is 
to be separated by decantation, dried and weighed. 

Process 3. — Immerse in the solution from which the bis- 
muth has been separated, a slip of clean iron, of known 
weight. This will precipitate the copper in the metallic 
form on the iron, which must be weighed again to find the 
weight of copper. Then evaporate the remaining liquor to 
dryness, with heat. 

Process 4. — Digest the dry mass of process 3, in a solu- 
tion of caustic ammonia. This will dissolve the cobalt and 
nickel, but not the iron. 

Process 5. — Drive off the excess of ammonia by heat, 
taking care not to continue the evaporation so as to pro- 
duce any precipitate, then add ca^ .stic potash to the solu- 
tion, and throw the whole on a f.iter, by which the nickel 
will be separated, while the clear liquor passes the filter. 

Process 6. — Boil the clear liquor, Avhich has passed the 
filter, and oxide of cobalt will fall, and continue the evapo- 
ration to dryness. 

Process 7. — Mix the oxide obtained by the last process 
with charcoal powder, in a covered crucible, and submit it 
to a strong heat for half an hour, or until reduction is 
effected. A button of cobalt will be found at the bottom 
of the crucible. At first, the metal is bluish gray, but turns 
reddish gray by exposure to the air. It is brittle, difficult 
of fusion, and has a specific gravity of about 8. 

The result of each process being weighed, will show, 
not only the comparative quantity of each, but the sum of 
the whole will determine the per centage of the cobalt in 
the ore. 

BISMUTH. 

The ores of bismuth are rare, and in general it is found 
only in small quantities at a place. Most of the bismuth 
used in the arts, is obtained in the processes for making 
smalt, from the ores of cobalt. 

The ores of cobalt being roasted and broken into small 
pieces, are mixed with certain quantities of potash and 



ANALYSIS OF METALLIC SUBSTANCES 397 

ground flints. This mixture is put into large clay crucibles, 
and fused with a strong heat for 12 hours, at the end of 
which, the blue glass, or smalt, will be perfectly formed. 
At the bottom of the crucibles, the bismuth and nickel, 
(more or less of which are contained in the cobalt ores,) are 
found reduced to their metallic states. These are readily 
separated, in consequence of the low degree of heat required 
to melt the bismuth. 

Bismuth is found under the following forms, viz : 

Native bismuth The pure metal. 

Sulphuret of bismuth. Bismuth and sulphur. 

Oxide of bismuth, Bismuth and oxygen. 

The ores of the metal are very easily reduced, the pro- 
cess requiring only a blowpipe, and a piece of charcoal. 
The ore being fused, the charcoal absorbs the oxygen, and 
the metal instantly appears. 

TESTS FOR BISMUTH. 

The solutions of this metal are white, and water alone 
throws down a white oxide. 

Gallic acid. Greenish yellow. 

Ferro-cj^anate of potash, Light yellow. 
Alkalies, White precipitate. 

ASSAY. 

The assay of the ores of bismuth is easily effected. A 
given portion of the ore is to be digested in the form of pow 
der, in nitric acid, and the solution filtered, and washed with 
water, containing a little of the same acid, by pouring thir 
on the filter. The solutions being mixed, pour in 8 or 10 
times their quantity of pure water, when a copious white 
precipitate will fall, which is easily reduced to the metallic 
state with a little black flux, or charcoal, in a cmcible. The 
heat for this purpose must be gentle, and the crucible cov- 
ered, otherwise the metal, after its reduction, will be lost by 
sublimation. 

If the bismuth is mixed with other metals, which dissolve 
in nitric acid, they still remain in the solution, not being pre- 
cipitated by the mere addition of water, as in the case of 
bismuth 

ANALYSIS. 

Supposing the ore to be composed of bismuth, lead, iron, 
sulphur and silex 



398 ANALYSIS OF METALLIC SUBSTANCES. 

Process 1. — Pulverize the ore, and digest in nitric acid, 
with heat, until nothing more is dissolved ; silex and sulphur 
will remain, while the metals will be dissolved. Throw the 
whole on a filter, and wash by pouring on dilute acid: the 
sulphur and silex will remain, and must be collected, dried, 
and weighed. 

Process 2. — The clean liquor which passed through the 
filter, being diluted largely with water, the oxide of bismuth 
will fall, and after decanting the liquor, is to be dried, and 
reduced with black flux as above directed. 

Process 3. — The solution is now supposed to contain 
only lead and iron, both in the form of nitrates. On the 
addition of sulphate of soda, the lead will be thrown down 
in the form of an insoluble, heavy, white precipitate. This 
is to be collected by passing through the filter, dried and 
weighed. 

Process 4. — To the remaining solution, add caustic am- 
monia in excess, by which the oxide of iron will be thrown 
down, (while the liquor will assume a fine blue color,) and 
must be separated by the filter, and washed by more ammo- 
nia. The oxide being dried, may be reduced to the mag- 
netic state by heating in a covered crucible with some unc- 
tuous substance, as linseed oil. 

Process 5. — The ammoniacal solution of the last process 
must be a little more than saturated with some acid, and on 
immersing a slip of iron or zinc, the copper which it con- 
tains will be obtained in the metallic fonn. For this pur- 
pose the slip must be previously weighed, as already directed. 

REDUCTION. 

The methods of reducing the ores of bismuth, are very 
simple, it being only necessary that they should be broken 
into fragments, and thrown upon burning charcoal or wood. 
In some instances the workmen seek out a hollow tree, or 
stump, and having filled it with alternate layers of brush 
wood and ore, set the whole on fire, and when the fuel is 
consumed, and the place cold, they find the bismuth among 
the ashes. 

Uses. — The only use of bismuth, in its metallic fomi, is 
that of forming a very fusible solder, when tilloyed with 
other metals. 

The oxide of bismuth is prepared by precipitating it from 
a solution, in nitric acid, by means of water, as already di- 
rected. When a little muriatic acid is added to the nitric 



ANALYSIS OF METALLIC SUBSTANCES. 399 

solution, the precipitate is composed of small glittering 
scales, and in this state is sold by perfumers under the name 
of pearl powder^ and is used as a cosmetic ; but it is well 
known that the application of such substances soon render 
their use absolutely necessary, as the skin soon becomes 
permanently darkened thereby. 

ANTIMONY. 

This metal occurs under the following forms : 

Native antimony, Antimony, arsenic, silver, iron. 

Sulphuret of antimony, Antimony and sulphur. 

-r, J ,. ^ Antimony, sulphur and oxy- 

Ked antimony, < ./ ? r j 

Nickeliferous antimony, J ^"'^^^ur ^'''"''' "'''''^' 
White antimony, Antimony, oxygen and silex. 

Before the blowpipe, the ores of antimony are easily 
reduced, generally with the emission of a sulphureous and 
arsenical odor. By continuing the heat, the reduced metal 
is entirely dissipated, in the form of a white oxide. 

TESTS FOR ANTIMONY. 

The solutions of antimony in muriatic acid are thrown 
down by mere dilution with water. The precipitate is a 
white submuriate. ^ 

A plate of iron, Black powder of the metal. 

Sulphuretted hydrogen, Orange precipitate. 



The method of assaying the ores of this metal will be 
understood by the following analysis : 

Process 1. — A portion of the ore reduced, as usual, to fine 
powder, was digested with heat in a mixture of 4 parts of 
muriatic, and 1 of nitric acid, until every thing soluble was 
dissolved. The Hquor being filtered, there remained a resi- 
due of sulphur and siHca. This being dried, was placed in 
a spoon, and held over the flame of a spirit lamp, until the 
blue flame ceased, and consequently the sulphur had burned 
out. The loss of weight thus gave the proportion of sul- 
phur and silex. 

Process 2. — The filtered solution being now diluted with 
pure water, the submuriate of antimony fell down, which 
being dried, was reduced to the metalhc state, with a little 



400 ANALYSIS OF METALLIC SUBSTANCES. 

black flux, in a crucible. In doing this, the heat must nol 
be strong, lest the metal should be sublimed. 

Process 3. — The remaining liquor, reduced by evaporation, 
was diluted with water, when another portion of the anti 
mony was obtained, and added to the former quantity. 

Process 4. — The solution being now tested in small por- 
tions, in a test tube, was found to contain iron and lead. 
The iron was precipitated with caustic ammonia, and the 
lead afterwards, by sulphate of soda, both of which were 
r->duced by means of charcoal powder, in a crucible. 

Some of the ores of antimony contain silver, which may 
be known by the fall of an insoluble muriate of the metal, 
during the first process, and therefore mixed with the sul- 
phur and silica. In order to separate it, the first residue 
must be digested in hquid ammonia, which will dissolve the 
muriate of silver. On saturating this with muriatic acid, 
and immersing a slip of copper, the silver will be obtained 
in the metallic state. It is hardly necessary to repeat, that 
in all such cases, the slip of copper must be weighed, both 
before and after immersion. 

REDUCTION OF ANTIMONY. 

The reduction of this metal is very simple and easy. The 
ore, being broken into small pieces, is placed on the floor 
of a furnace so constructed that the flame will pass over it. 
This is called a reverheratory furnace. The heat is at first 
gentle, to drive off the sulphur, and afterwards increased, 
with the addition of charcoal, by which the metal is reduced 
to the metallic state. 

The antimony thus obtained is impure, being almost 
always mixed with portions of some other metal, as lead, 
copper, or arsenic, and therefore for chemical or medicinal 
purposes, must be dissolved in nitromuriatic acid, precipi- 
tated with water, as above directed, and then reduced by 
charcoal, or flux. 

LEAD. 

The ores of lead are very numerous, the metal being min- 
eralized by several of the metallic and mineral acids, as 
well as by phosphorus, sulphur, and oxygen. They differ 
very materially in appearance and weight, in consequence 
of the different agents by which they are mineralized, and 
the substances with which they are combined. Some of 
them, as the sulphuret, are rich in the metal, while others 
are not worth working. 



ANALYSTS OF METALLIC SUBSTANCES. 40 1 



VARIETIES 

Salphuret of lead, Lead and sulphur. 

Oxide of lead, Lead and oxygen. 

Carbonate of lead. Lead and carbonic acid. 

Muriate of lead, Lead and muriatic acid. 

Phosphate of lead, Lead and phosphoric acid. 

Arseniate of lead, Lead and arsenic acid. 

Sulphate of lead. Lead and sulphuric acid. 

Molybdate of lead, Lead and molybdic acid. 

Chromate of lead. Lead and chromic acid. 

With respect to the composition of these varieties, we 
have only named the principal ingredients, and from which 
they have derived their names; but in addition to these, 
nearly every lead ore, except the sulphuret, contains foreign 
admixtures, as copper and iron, and in most cases, the ores 
named are mixed with each other, so that the muriate, or 
carbonate, will perhaps contain both these ores, with the 
addition of chromate, sulphate, &c. Most of these ores, 
however, may be reduced to the metallic state with the 
blowpipe, on charcoal, 

TESTS FOR LEAD. 

Sulphate of soda, White precipitate. 
Ferro-cyanate of potash, do. do. 

Infusion of galls, do. do. 

Sulphuretted hydrogen, Black precipitate. 

ASSAY, 

Notwithstanding the complicated admixture of these ores, 
their assay is sufficiently simple. Reduce a given weight 
of the ore to powder, and place it on a muffle, and apply a 
degree of heat just sufficient to volatilize the arsenic and 
sulphur, or until, on moving the muffle from the fire, the 
smell of these substances are no longer emitted. Having 
thus finished the roasting, the ore is to be levigated, mixed 
with two or three times its weight of black flux, and a httle 
muriate of soda, and exposed in a cn.icible to a strong heat. 
When the crucible is cold, a button of lead will be found at 
the bottom, which, on being weighed and compared with 
the weight of the ore, will show the percentage. 

If the ore to be assayed is galena, its own weight of black 
flux will be sufflcient to eflect its reduction, it first being 
roasted as above directed, and pulverized. 



402 ANALYSIS OF METALLIC SUBSTAJNCLS. 

In the roasting of lead ores, care must be ta^en not to 
fuse them, as it is much more difficult to dissipate their 
volatile parts, after fusion, than before. 

ANALYSIS. 

Supposing the ore to be the carbonate of lead, mixed with 
green oxide of copper, and oxide of lead, its analysis may 
be performed as follows : 

Process 1. — Having roasted the ore, put 100 grains into 
a flask, the weight of which had been previously ascertained, 
and pour on it by degrees a quantity of nitric acid, diluted 
by its own weight of water, the weight of the acid being 100 
grains. Effervescence will instantly begin, which having 
subsided, the comparative weight of the bottle and its con- 
tents, will show the weight of the carbonic acid which 
escaped. 

Process 2. — The clear liquor being decanted into a tall 
glass jar, drop in a solution of sulphate of soda, until a white 
powder ceases to fall. The sulphate of lead thus separated 
must be washed, dried, and reduced with black flux, or the 
quantity of lead may be readily estimated by the proportions 
of the metal and acid in the salt. 

Process 3. — The copper now remaining in the solution, 
may be obtained by immersing in it a plate of iron, or zinc, 
and suffering it to remain at rest for 24 hours ; the copper 
will thus fall in the metaUic state. If on testing the solu- 
tion with ammonia, a blue tint is given it, copper still re- 
mains, and a gentle heat must be applied, the metalKc plate 
remaining in its place, when the whole of the copper will 
fall, and being collected may be melted into a button,. or by 
finding the addition to the weight of the plate of iron, or 
zinc, its weight is known. 

REDUCTION. 

The great quantities in which the ores of lead are found, 
together with its cheapness, and the facility w4th which it 
is reduced, render it unnecessary to observe that care and 
nicety in its reduction that are observed with respect to the 
more scarce and valuable metals. 

Galena is the only ore which is worked for the express 
purpose of obtaining this metal. This is selected as free as 
possible from stony matter, and after being broken, is roasted 
in large furnaces, built for the purpose. By this process 
the sulphur and arsenic, if it contains the latter, is driver 



ANALYSIS OF METALLIC SUBSTANCES. 403 

off. and the ore is. brought to a proper state for the smehmg 
furnace, where it is thrown in, mixed with charcoal. The 
heat of the furnace is urged bj bellows, and is kept red 
until the ore melts, and running through the charcoal, is 
reduced to the metaUic state. It is let out at the bottom of 
the furnace, and cast into pigs for market. 

Most of the lead of commerce contains a small quantity 
of silver, and in some instances the ores of this metal con- 
tain a quantity sufficient to pay the expense of extracting it. 
When the silver amounts to 12 or 14 ounces to the ton of 
lead, the former is separated by exposing the lead to a high 
degree of heat, in a furnace so constructed that the air shall 
constantly pass over the heated metal, and by which it is 
oxidated, or converted into litharge, while the silver remain- 
ing unchanged, is collected and refined. 

The litharge is afterwards reduced to the metaUic state, 
by the simple process of melting it with charcoal in a close 
furnace, by which the oxygen is absorbed by the burning 
fuel. 

COPPER. 

Copper is often found in the native state, but more gene- 
rally in small quantities. That which is used in commerce 
and the arts, is chiefly extracted from its ores, which are 
very numerous, it being found combined with oxygen, sul- 
phur, arsenic, carbonic acid, sulphuric acid, muriatic acid, 
&c. The following are among the most important species 
of this ore : 

Sulphuret of copper. Copper, sulphur and iron. 

Gray copper, Copper, sulphur, iron and arsenic. 

Red oxide of copper. Copper and oxygen, and iron. 

Carbonate of copper, Copper and carbonic acid. 

Muriate of copper, Copper, muriatic acid, and water. 

Phosphate of copper. Copper and phosphoric acid. 

Sulphate of copper. Copper and sulphuric acid. 

Arseniate of copper. Copper and arsenic acid. 

Like the ores of lead, those of copper are variously inter- 
mixed, and often contain several more ingredients than are 
mentioned as belonging to their composition. For the de- 
scription of these ores, the author must refer to his treatise 
on Mineralogy, where an account of each will be found. 

TESTS FOR COPPER. 

It is understood of course, that the metal is dissolved in 
some acid, to saturation, before the application of the test. 



404 ANALYSIS OF METALLIC SUBSTANCES. 

Plate of iron, Metallic copper. 

Potash, Green precipitate. 

Ammonia, Azure blue color. 

Ferro-cjanate of potash, Reddish brown precipitate. 

Infusion of galls, Brown precipitate. 

Sulphuretted hydrogen, Brownish black precipitate. 

ACTION OF THE BLOW- PIPE ON COPPER ORES. 

The oxides of copper maybe reduced on charcoal by tliu 
blow-pipe. The carbonates are infusible without addition, 
but with borax form a green glass, and yield a metaUic glo- 
bule. The varieties containing sulphur and arsenic, yield 
white fumes, and give the odor of these substances respec- 
tively. 

ASSAY OF COPPER ORES. 

As nearly all the ores of copper contain sulphur or ar- 
senic, or both, they must in the first place be roasted with a 
gentle heat, in order to expel these substances. After this 
is done, the ore is to be pulverized, and mixed with twice 
its weight of black flux in a crucible, and exposed to a 
strong heat, as that of a smith's forge, for about half an 
hour. Should the globules of revived metal not readily 
form a button at the bottom, a little common salt thrown in, 
will render the fusion more complete. The little mass of 
pure copper will show the percentage of metal in the ore. 

ANALYSIS OF COPPER ORES. 

Process I. — Having roasted a specimen of the sulphuret 
of copper, previously weighed, on weighing it again, th^ 
amount of sulphur will be known. Then pulverize and di 
gest in nitric acid, which will dissolve the copper and iron 
it may contain. Filtrate the solution, which will separate 
the silex and any sulphur which the roasting did not expel. 
These being dried and weighed, the sulphur may be burned 
away in a spoon. The weight of silex will thus be known. 

Process 2. — Precipitate the copper from the solution with 
a slip of clean iron, suffering the whole to remain at rest for 
24 hours. The iron being weighed before, and after immer- 
sion, will show the weight of copper. 

Process 3. — Add caustic ammonia to the remaining solu- 
tion, which will throw down the iron in the state of an 
oxide. Then filter, and collect the iron, estimating the 
weight of the metal by that of the oxide, as shown by the 
table of equivalents. 



ANALYSIS OF METALLIC SUBSTANCES. 405 

Process 4. — If the liquid is colored blue by the ammonia, 
it still retains copper, and must be acidified with nitric acid, 
and the bar of iron again immersed, and the action assisted 
by a gentle heat, when all the copper will fall on the iron, 
and its weight must be added to the former. 

Considerable experience is necessary, in order to make a 
satisfactor}^ analysis of a copper ore, especially when it 
contains but a small quantity of the metal, mixed as these 
ores often are, with a variety of foreign ingredients. In 
making the assay, also, a good deal of patience is often re- 
quired, and the process several times repeated, before the 
result can be depended upon, unless the operator has had 
much experience in the art of analysis. 

In Germany, where the arts of smelting and refining the 
metals are carried to a high degree of perfection, every 
parcel of copper ore is assayed by three several persons 
before its reduction. 

REDUCTION OF COPPER ORES. 

The sulphuret of copper is one of the most abundant 
ores, and it is from this species that most of the copper of 
commerce is obtained. The processes are lengthy, requir- 
ing several months before the metal is ready for market. 

The ore, which is often contained in slate stone, is first 
broken into small pieces, and roasted in kilns with wood. 
A small quantity of fuel is, however, only required for this 
purpose, for the quantity of sulphur is such, that after it is 
once set on fire, the mass continues to burn, when the quan- 
tity of ore is great, for four or five months, without further 
addition of fuel. 

When the ore ceases to burn, this part of the process is 
finished, and the sulphur which has sublimed by the heat, 
and is retained in long chimneys, is removed. The ore is 
then transferred to a reverberatory furnace, and mixed with 
charcoal, where it is submitted to a white heat for several 
hours, when the copper in the metallic state, but mixed with 
many impurities, is obtained. It is afterwards refined, by 
being repeatedly melted with charcoal, and granulated, by 
pouring it into water, when it becomes malleable copper. 

In those ores of copper which contain arsenic, the slow 
roasting above described is omitted, the ore being at once 
thrown into the furnace, and the sulphur and arsenic dissi- 
pated in a few hours. In some establishments the refining 
is done by mixing the impure copper with a portion, say 6 



406 ANALYSIS OF METALLIC SUBSTANCES. 

per cent, of lead, and stirring the melted metals together, 
bj which means, the lead unites with the impurities, and 
both are skimmed off together. The workmen consider 
the process finished, when, on dipping in an iron rod, and 
then plunging it into water, the copper with which it is 
coated, readily separates from the iron. 



The ores of tin have been found in but a few localities. 
They are always found in primitive rocks, generally in 
granite, and are associated with copper, and iron. Its chief 
varieties are : — 

Oxide of tin, Tin, oxygen, iron, and silex. 

Wood tin, Oxides of tin, and iron, 

Sulphuret of tin, Tin, sulphur, copper and iron. 

The oxide of tin occurs disseminated, massive, and in 
crystals, often of regular, and beautiful forms. Wood tin 
is of light brown color, and when broken, sometimes resem- 
bles in texture the grain of wood, or root of a tree, hence 
the name wood tin. It is a purer oxide than the above 
variety, which is called tin stone. Sulphuret of tin is the 
most impure variety, being mixed with copper, iron, and 
often other impurities. 

ACTION OF THE BLOWPIPE ON THE ORES OF TIN. 

The oxides of tin, before the blowpipe, decrepitate strongly, 
but when in powder and mixed with charcoal, are reduced 
to the metallic state, though with considerable difficulty. 
The sulphuret, treated in the same manner, melts into a 
dark scoria, but is not reduced. 

TESTS FOR TIN. 

The salts of tin are uncolored, or white. The tests for 
solutions holding the metal in the state of protoxide, are as 
follow : 

Muriate of gold, Purple precipitate. 

Muriate of platina. Orange do. 

Ferro-cyanate of potash, White do. 

Per-chloride of mercury. Black do. 

Plate of lead, Metallic tin. 

Metallic tin has a silvery lustre, not readily tarnished by 
exposure. It always may be known from other metals by 
the peculiar crackhng noise it makes on being bent. 



ANALYSIS OF METALLIC SUBSTANCES. 407 



ASSAY OF TIN. 

In the dry way, the assay of tin ores is sufficiently simple. 
Having reduced 100 grains of the ore to powder, place it in 
a crucible, and expose it to a low red heat, by which the 
sulphur and arsenic, if it contain any, will be dissipated. 
The ore is then to be mixed with charcoal, moistened with 
a little linseed oil, and exposed to a bright red heat, in a 
covered crucible. A button of the metal will be found at 
the bottom, which, on being weighed, will show the per 
centage the ore contained. 

ANALYSIS OF THE ORE. 

Process 1. — Mix the ore, being reduced to powder, with 
five or six times its weight of caustic potash, and submit the 
mixture to a red heat for half an hour in a silver crucible. 
Digest the gray mass thus formed, in hot water, and if any 
insoluble matter still remains, it must be mixed with more 
alkali, and again heated as before. 

Process 2. — Filter the alkaline solutions, and if any thing 
remains, dissolve it in muriatic acid, and add this to the alka- 
line solution, which must be super-saturated with muriatic 
acid, and then evaporated to dryness. The dry mass must 
now be digested in hot water, which will take up all except 
the silex, which will remain after filtration. 

Process 3. — The tin and copper, if the ore contained any, 
will now be contained in the muriatic solution, which is to 
be saturated with carbonate of potash, when a precipitate 
will fall. If this is white, it is to be collected, and the pro- 
cess ended by reducing it with charcoal powder, and a little 
oil or resin. But if it has a greenish appearance, it contains 
copper, and the precipitate must be re-dissolved in muriatic 
acid, when, on the immersion of a slip of tin of known 
weight, the copper will cover it in the metallic state, and 
the difterence of weight will show that of the copper. 

Process 4. — The solution being now deprived of the cop- 
per, a plate of zinc immersed in it will throw down the tin 
in its metalhc state, which, when dried and fused, will indi- 
cate the per centage contained in the ore. 

REDUCTION OF TIN ORES. 

The reduction of what is called mine tin, that is, ore 
which is extracted from the mines at Cornwell in England, 
is reduced in the following manner. The ore is first stamped 



408 ANALYSIS OF METALLIC SUBSTANCES. 

or pounded, and at the same time washed by a nmning 
stream, which carries aAvay much of the earthy matter. It 
is then sent to the furnace to be roasted, after which it is 
again washed in order to purify it as much as possible The 
ore thus prepared, is mixed with coal and a portion of slacked 
lime, and smelted in a reverberatory furnace, which is about 
seven feet long, five broad, and fifteen inches deep. The 
usual charge of ore is 7 cwt, which yields about two thirds 
of its weight of tin. 

To obtain 100 pounds of tin, there is consumed in the 
roasting, 38 pounds of coal, and in the smelting, 170 pounds 
of coal, in all 208 pounds, or a little more than twice the 
weight of the tin obtained. 

REFINED BLOCK TIN. 

The tin obtained by the above process, is afterwards 
refined by melting it w^ith a gentle heat, in a reverberatory 
furnace, and allowing it to run off as fast as it becomes liquid, 
into an iron kettle, with a small fire under it. Thus the 
least fusible substances with which the metal is alloyed, are 
left behind. The tin in the kettle is kept fluid, and is further 
purified by taking it up in small quantities at a time, and 
pouring back again, by which the more oxj'dable parts are 
made to swim on the surface, and are slammed off. 



The ores of this metal are not numerous, nor are they 
very universally diffused, though, in small quantities, they 
often occur among the ores of lead. The principal varie- 
ties of zinc are the following : 

Sulphuret of zinc. Zinc, sulphur, and iron. 

Red oxide of zinc. Zinc, oxj^gen, iron, and manganese. 

Electric calamine. Zinc, oxj^gen, and silex. 

Sulphate of zinc. Zinc, sulphuric acid, and water. 

Carbonate of zinc. Zinc and carbonic acid. 

ACTION OF THE BLOW -PIPE ON ZINC ORES. 

Before the blowpipe, on charcoal, the ores of zinc first 
evolve their volatile parts, as sulphur, and by continuing the 
heat, some of them become white, or form scoria, while oth- 
ers emit white fumes, which is an oxide of the metal. With 
glass of borax, they form a kind of translucent enamel, or 
if copper is present, the enamel is green. In the dry vray, 
therefore, the tests of this metal are not satisfactory. 



ANALYSIS OF METALLIC SUBSTANCES. 409 



TESTS FOR ZINC 



This metal is readily dissolved in all the mineral, and 
in several of the vegetable acids. The tests for its presence 
in solutions are b}^ no means decisive, many substances 
throwing down merely a white precipitate. The best method 
therefore, to detect its presence, is to have recourse to dis- 
tillation in the manner described for arsenic, only that more 
hoat is required for the zinc. This method is as follows : 

ASSAY OF ZINC ORES. 

The ore, in the first place, is to be roasted with a gentle 
heat. If the heat is carried to redness, the metal will be 
sublimed ; the roasting is only intended to get rid of the 
sulphur and arsenic. After roasting, the ore must be redu- 
ced to fine powder, and mixed with lamp-black, or charcoal 
powder, and introduced into a green glass retort, and ex- 
posed to a red heat. The metal will rise by sublimation, 
and will be condensed in the neck of the retort, which must 
be loosely stopped, or dipped into a small quantity of water. 
The weight of the metal may be known by weighing the 
ore and charcoal, both before and after the process. 

ANALYSIS OF ZINC ORES. 

Process 1. — Reduce a given weight to fine powder, and 
as some varieties are hydrates, submit to the temperature 
of boiling oil, or mercury ; this will drive off the water, the 
loss of which must be estimated. 

Process 2 — Digest the ore without heat, for two or three 
days, in dilute nitro-muriatic acid ; if any caloric is gene- 
rated in the process, it should be kept down by immersing 
the vessel containing it in cold water ; stir the mixture occa- 
sionally with a glass rod, and pour off the clear liquor; 
repeat the process of immersion, and well wash with hot 
water. The residue after this will be sulphur and silex ; 
separate by burning over the flame of a spirit lamp. Esti- 
mate the quantity of sulphur thus lost. , 

Process 3. — Examine the residue, supposed to be silex; 
it may have a portion of sulphate of lead intermixed ; if this 
is the case, digest the whole in sulphuric acid ; this will 
take up the lead, which is to be separated from the undis- 
solved silex, and the former may be decomposed at a boiling 
temperature in a solution of carbonate of potash. Carbon- 
ate of lead will fall, which should be collected, dried, and 
IS 



410 ANALYSIS OF METALLIC SUBSTANCES. 

reduced to the metallic sta*,e. To ascertain the quantity of 
sii.i^hur acidified by the nitric acid, and which was combined 
with the lead, but now with the potash, note the difference 
in the weight of the residues, before and after digestion with 
the sulphuric acid ; this will give the quantity of sulphate 
of lead, from which the equivalent quantities of acid and 
lead may be estimated. 

Process 4. — The solution, No. 1, may now be tested for 
any free sulphuric acid, and acetate of barytes added, until 
no further precipitation ; this is to be collected, dried, ana 
its equivalent of sulphur obtained and added to the former 
quantities ; this method will give the whole of the sulphur 
contained in the ore. 

Process 5. — Or, the residual solution may be tested for 
lead, and, if it contains any, which will be the case if any 
sulphate of this metal was found in the residue, it may be 
thrown down by the sulphate of soda. 

Process 6. — Test a drop of the hquor with caustic am- 
monia, and if a blue tinge is perceptible, it contains copper, 
which is to be thrown down by inserting into the acid solu- 
tion, a clean plate of iron, of known weight, as before 
mentioned. 

Process 7. — Decompose the solution, now holding zinc 
and iron, by carbonate of soda; the carbonate of zinc, and 
oxide of iron, will be thrown down. Digest the precipitate 
in ammonia, the zinc will be dissolved, while the iron re- 
mains, and which may be reduced to the magnetic state 
by heating in a crucible with charcoal. 

Process 8. — The ammonial solution may now be slightly 
super-saturated with muriatic acid, and carbonate of soda 
added ; the carbonate of zinc will thus be obtained pure, 
and may be brought to the metaUic state with a httle char- 
coal, or black flux in a retort, or close crucible, heated to 
redness. — Joyce's Chemical Mineralogy. 

REDUCTION, 

The method of reducing the ores of zinc, is said to have 
been introduced into Europe from China, and that a person 
was sent to that country expressly for the purpose of obtain- 
ing the secret. For this purpose, the ore is broken intc 
small pieces and submitted to a gentle heat in a reverberators 
furnace, until the carbonic acid, sulphur, and other volatile 
substances are driven off. This being done, the ore is re- 
moved and placed in large jars made of clay, on which 



ANALYSIS OF METALLIC SUBSTANCES. 41} 

air-tight covers are luted. Each jar has an iron pipe whicn 
passes down through the floor of the furnace, and dips into 
water. The furnace is of sufficient length to contain eight 
or ten of these jars. The jars being filled with ore, and 
the covers luted on, a fire is kindled in the furnace, the heat 
of which raises the zinc hy sublimation, and passing 
through the open pipes, it falls down, and is condensed in 
the metaihc forai, in the water below. The whole process, 
therefore, is merely a dry distillation. 

Zinc is a cheap and abundant metal. It is not only em- 
ploj^ed in the form of sheets to cover the roofs of buildings, 
and other purposes, but also forms a component part of brass, 
one of the most useful of alloys. In making this composi- 
tion, metaihc zinc is not employed, since the heat necessary 
to melt the copper, would raise the zinc by subHmation, and 
drive it away without effecting the object. The copper, 
therefore, in sheets, is placed between layers of calamine, 
(native carbonate of zinc,) in melting pots, and on the ap- 
plication of fire, the zinc sublimes from the ore, and com- 
bines with the copper, now at a red heat, the whole after- 
wards running down to the bottom of the pot, in the state 
of brass. 

It is a curious fact, that brass was known and employed 
in the arts, for a long time before it was even suspected that 
any such metal as zinc existed. It was known by experi- 
ence, that a certain earth, as it was thought, called Cala- 
mine, when heated with copper, changed that metal to a 
yellow color, and added considerably to its weight. But the 
ancient manufacturers of brass, it appears, never had a 
thought that the earth they employed was the ore of a 
metal, until the metal itself happened by accident to be 
produced. 

IRON. 

Tliis metal, in one form or another, is much more univer- 
sally diffused than any other, there being no mineralizing 
substance with which it is not found in combination. The 
ores of iron are, therefore, very numerous. For a descrip- 
tion of the forms, colors, and composition of these ores, the 
author must refer the student to his " Introduction to Mine- 
ralogy," where the distinctive characters, and definite 
analysis of each species is given. The general composition 
of the principal species of iron ore are the following : 



412 ANALYSIS OF METALLIC SUBSTANCES. 

Native iron. Iron, lead and copper. 

Meteoric iron, Iron and nickel. 

Arseniate of iron. Iron, oxygen and arsenic. 

Sulphuret of iron, Iron and sulphur. 

Oxide of iron, Iron and oxygen. 

Red iron ore, Iron, oxygen, silex and lime. 

Brown iron ore. Iron, oxygen, manganese, and silox. 

Bog iron ore, Iron, oxygen, clay and manganese. 

Specular oxide of iron, Iron and oxygen. 

Spathose iron ore, Iron, oxj^gen and carbonic acid. 

Phosphate of iron. Iron and phosphoric acid. 

Chromate of iron. Iron and chromic acid. 

These are the principal ores of iron, though the list is far 
from contaming the names of all the varieties known and 
enumerated. The ores of iron which furnish most of the 
metal, are the oxides, and the bog ore. 

ACTION OF THE BLOW -PIPE ON IRON ORES. 

Several of the ores of iron are magnetic in their native 
states, and this in general may be considered a sufficient 
test of the presence of the metal. These ores contain at 
least some particles of iron in the native state. The oxides 
of iron do not move the magnet, until submitted to the action 
of the blow-pipe, when most of them, if this is done in con- 
tact with charcoal, or some other combustible matter, be- 
come distinctly magnetic. Some of these ores, after a long 
application of the heat, are reduced to a sort of cast iron, 
but more generally they form a shapeless slag, of a black 
color, which has no other indication of iron, than that of 
being lifted by the magnet. 

TESTS FOR IRON. 

Infusion of galls. Black precipitate. 

Ferro-prussiate of potash, Blue do. 

Sulphuretted hydrogen. Black do. 

The most ready test for iron, in any saturated, or dilute 
solution, is infusion of galls, or a little piece of the nutgall 
Itself, suspended in the solution. In either case, a dark 
precipitate will gradually fall. 

ASSAY OF IRON ORES. 

Before attempting the assay, the ore should be roasted 
with a strong red heat, as long as any vapor, or smell arises. 



ANxlLYSIS OF METALLIC SUBSTANCES. 413 

After this, two parts of the mineral are to be intimately 
mixed bj trituration, with one of fluor spar, one of charcoal, 
and four of common salt, by weight. This mixture is to be 
put into a covered crucible, and exposed to a white heat for 
an hour, after which, if the operation has bcQn well per- 
formed, a button of cast iron will be found at the bottom of 
the crucible, and by which the per centage of metal in the 
ore may be found. 

If the ore contains much stony matter, one part of black 
flux should be added to the above mixture. The common 
salt, and fluor spar in the above process, act as fluxes, while 
the charcoal absorbs the oxygen from tl^e metal. 

ANALYSIS OF IRON ORES. 

There is, in general, no great difficulty in the analysis of 
the ores of iron. The pitchy ore, which is a sulphuric oxide 
of the metal, often containing manganese, may be treated 
as follows: 

Process 1. — Pulverize the ore, and introduce a given 
weight into a flask, and pour on such a quantity of dilute 
muriatic acid as will take up every thing soluble, then fil- 
ter, and wash the residue with water. 

Process 2. — Add together the solution and washings of 
the above process, and drop in solution of muriate of barytes 
until no further precipitation takes place. The precipitate 
will be sulphate of barytes, formed by the mutual decom- 
position of the muriate of barytes added, and the sulphate 
of iron in the solution. To separate these, the solution 
must again be filtered, washed, dried, and weighed, and the 
quantity of sulphuric acid in the sulphate of barytes, esti- 
mated by the scale of chemical equivalents. 

Process 3. — The filtered liquor now contains the iron and 
manganese. This is to be concentrated by evaporation, and 
a small quantity of nitric acid added, in order to render tho 
iron a peroxide, and make it more readily separable. Caus- 
tic ammonia in solution must now be poured in, in excess, 
by which the iron will be precipitated, and can be obtained 
by decanting the liquid, after which it may be brought to 
the magnetic state, by heatmg in a crucible, with resin, or 
linseed oil. 

Process 4. — The excess of ammonia must be driven oflf 
by heat, after which the oxide of manganese will fall, and 
after being dried, its weight found. In this manner the 
weight of iron in a given quantity of the ore is determined. 



414 ANALYSIS OF METALLIC SUBSTANCE. 

In cases where much silex is mixed with the ore, as in the 
specular and magnetic oxides, where the acids have Httle 
effect in their native state, these are to be fluxed with three 
or four times their weight of potash, after which the muri- 
atic acid will readily effect a solution of the whole of the 
iron, and which is then to be precipitated with ammonia, 
and after drying, brought to the magnetic state, as above 
directed. 

REDUCTION OF THE ORES OF IRON. 

The ore is broken into small pieces by the aid of the 

stamping mill, wLich consists of several pieces of wood, 
shod with iron, which are alternately Hfted up, and let fall 
on the ore contained in a strong box. The machinery foi 
this purpose is moved by means of water or steam. 

After the ore is broken, it is roasted, to drive off the sul- 
phur and other volatile matters. It is then transferred to 
the smelting furnace, where it is mixed with charcoal and 
lime, or sometimes with oyster shells, and melted, and thus 
becomes impure cast iron, or when cast into moulds, is 
known by the name of pig iron. 

The pig iron is next broken in pieces and removed to 
another furnace where, in England, it undergoes the pro- 
cess called puddling^ for which, many years ago, a patent 
was obtained. This operation consists in placing the bro- 
ken pigs in a reverberatory furnace, and when in fusion, 
stirring it with iron bars, so that every portion may be ex- 
posed to the air and flame. After a time the mass swells, 
emits a blue flame, and gradually becomes tenacious and 
less fusible, and at length is granulated or converted into 
small separate pieces. The fire is then urged so that these 
particles again agglutinate, and at a welding heat are again 
brought into masses. In this state of intense heat, the 
masses are passed in succession between iron rollers, by 
which a large quantity of extraneous matter is pressed out, 
and the iron becomes malleable. The sheets thus formed 
are then cut into bars, and again heated and hammered by 
means of a great mass of iron lifted by machinery, and thus 
become the malleable iron of commerce. For a detailed 
account of the processes of working iron, the reader is 
referred to "Aikin's Dictionary of Chemistry," and for the 
construction of furnaces for the smelting of this and other 
metals, to "Gray's Operative Chemist." 



A^AJ^YSIS OF METALLIC SUBSTANCES. 4i5 



CHROMK. 

The color of this metal is between tin white and steel 
graj. It is obtained from the chromate of iron, which is 
found native in various places. The metal is of no use in 
the arts, but its salts, especially the chromate of lead, is 
employed extensively as a pigment. 

The ores of chrome are the following: 

Oxide of chrome, Chrome and oxygen. 

Chromate of iron, Chromic acid and iron. 

Chromate of lead, Chromic acid and lead. 

ACTION OF THE BLOW- PIPE.- 

The green color of the oxide of chrome is changed to 
yellow by the blow-pipe. With borax it forms a green 
glass. The chromate of iron is infusible alone, but with 
borax fuses into a bead of a rich and lively green. The na- 
tive chromate of lead also forms a green bead with borax. 

TESTS FOR CHROME. 

The solutions of chrome are readily and strikingly dis- 
tinguished by the fine yellow precipitate they form with 
nitrate of lead, which, when dried, is known under the 
name of chrome yellow. With other nitrates the solutions 
of chrome form precipitates as follow : 

Nitrate of mercury. Rich cinnabar precipitate. 
Nitrate of silver, Carmine, changing to purple. 

Nitrate of copper. Chestnut precipitate. 

ASSAY OF THE ORES OF CHROME.' 

As metalhc chrome is useless, and difficult to obtain on 
account of the intense heat necessary for its fusion, all that 
is necessary in the assay, is to ascertain the quantity of 
oxide the ore contains. 

Process 1. — Reduce a known portion of the chromate of 
iron to a fine powder, and mix it with half its weight of 
nitre, and expose to a red heat in a crucible, for an hour, 
or until all the nitrous gas is expelled. By this process the 
chromic acid is absorbed by the potash of the nitre, and a 
chromate of potash is formed, while the oxide of iron re- 
mains free. 

Process 2. — Dissolve the chromate of potash with hot 
water, and separate the oxide by filtering through cloth 



416 ANALYSIS OF METALLIC SUBSTANCES. 

Test the liquor with sulphuric acid, when, if there arise the 
fumes of nitric acid, it shows that undecomposed nitre still 
remEiins, and probably chromic acid, and chromate of iron 
also. If it contain the latter, the solution must be evapo- 
rated to dryness, again mixed with nitre and fused, and the 
chromate of potash dissolved out as before, and this liquor 
added to the former. 

Process 3. — The whole liquid must now be saturated 
with nitric acid, which generally throws down some earthy 
matter; filter this, and pour in solution of nitrate of mercury 
until no further precipitation takes place ; throw the whole 
on a paper filter. Collect and dry the red chromate of mer- 
cury thus obtained. 

Process 4. — In order to obtain the oxide of chrome, the 
chromate of mercury obtained above must be placed in a 
retort, or muffle, and a moderate heat applied ; the mercury 
will thus be expelled, and the green oxide of chrome will 
remain, from which can be estimated the per centage of 
chromate of iron in the ore. 

ANALYSIS OF THE CHROMATE OF LEAD. 

The color of the native chromate of lead is various tints 
of red, often very beautiful. Its composition is oxide of lead 
64, chromic acid 36. 

Process 1. — A given weight of the powdered ore is 
placed in a clean iron, or unglazed earthen vessel, and on 
it poured a solution of 3 or 4 parts of carbonate of potash 
in water ; boil with a gentle heat until the chromate of lead 
is decomposed, when there will be in solution carbonate of 
lead and chromate of potash : pour the whole on a filter, 
and having washed, dry the residuum, which will be car- 
bonate of lead. Should any yellowness remain, this powder 
must again be boiled with potash as before, and the whole 
added together, filtered, and reduced to metallic lead by 
fusion with charcoal or black flux. 

Process 2. — The chromic acid may be readily obtained 
from the remaining solution, thus : Acidulate the solution 
with nitric acid, and then add muriate of barj^tes until no 
further precipitate falls. Collect the chromate of barytes, 
thus formed, on a fii^er. 

Process 3. — The cLromate of barytes of the last process 
is to be digested in dilute nitric acid, in quantity just suffi- 
cient to dissolve it ; then add sulphuric acid and the sul- 



ANALYSIS OF METALLIC SUBSTANCES. 417 

phatc of barytes will be precipitated, leaving the chromic 
acid in solution. 

Process 4. — The solution must now be evaporated, when 
crj^stals of red chromic acid will form, the weight of which 
will show bj estimation the per centage of the chromate of 
lead the ore contained. 

URANIUM. 

In the metalHc state, uranium is of no use, but some of 
its oxides are used as a coloring matter for porcelain. Its 
ores are rare, and generally occur only in small quantities. 
Black oxide of uranium, > Oxide of uranium, with lead, 
Green oxide of uranium, y copper, iron, and silex. 

ACTION OF THE B L O W - P I P E . 

The ores of uranium are infusible alone, but with borax 
they form a dark slag. They dissolve in nitric acid, with 
emission of nitrous fumes. 

TESTS FOR URANIUM. 

The salts of this metal are yellow, or greenish yellow. 
Alkalies, Yellow precipitate. 

Hydro-sulphate of ammonia. Dark brown do. 
Ferro-cyanate of potash, Fine brown do. 

Hydriodic acid. Reddish yellow do. 

ANALYSIS. 

Process 1. — The species, black oxide of uranium, may 
be thus analysed. Digest a given quantity of the ore finely 
powdered, with four or five parts of dilute nitric acid, until 
all action ceases, and the addition of more acid produces 
no effect ; sulphur and silica will remain after filtration, and 
may be separated by burning away the sulphur, and the 
weights of each ascertained. 

Process 2. — To the filtered solution, add sulphate of 
soda, which will precipitate the lead, in form of a sulphate ; 
collect and dry this, and estimate the quantity, or reduce to 
the metallic state with charcoal. 

Process 3. — The solution now remaining is to be mixed 
with caustic potash, when a precipitate will fall, which, 
after being separated by filtration, must be digested in a so- 
lution of caustic ammonia, by which the copper will be 
dissolved, and may be obtained and weighed, by slightly 
super-saturating the ammoniacal solution with an acid, and 
then immersing a slip of clean iron or zinc, as formerly 
directed with respect to copper. 
18* 



418 ANALYSIS OF METALLIC SUBSTANCES. 

Process 4. — The oxides of uranium and iron now remain 
in the Hquid, to which must be added some fresh nitric acid, 
in order to effect their entire solution, after which caustic 
ammonia is to be poured in, which will precipitate the ox- 
ides of uranium and iron. These are to be collected by 
filtration, and washed and dried, mixed with a httle mu- 
riate of ammonia, and thrown, by small parcels at a time, 
into a red hot crucible, by which, according to Mr. Joyce, 
the iron will be removed, while the oxide of uranium will 
remain. 

Or, the mixed oxides may be boiled in a solution of bi- 
carbonate of potash, which will take up the oxide of ura- 
nium, and leave the iron ; to obtain the first, super-saturate 
the solution with muriatic acid, and precipitate with caustic 
ammonia; or, the iron may be precipitated by a slip of 
zinc, and the mixed oxides of uranium and zinc obtained 
by precipitation with caustic potash, and treated with pure 
ammonia, which will dissolve the zinc, and leave the ura- 
nium in solution. 

The metal may be obtained by evaporating the above 
liquid, and heating the oxide intensely with charcoal pow- 
der. It is a brittle metal, of a gray color. 

PLATINUM. 

This metal is found in the form of small grains, resem- 
bling in color and appearance coarse iron filings, only that 
their sharp angles are rounded. Sometimes masses are 
found of the size of a filbert, but these are very rare, the 
medium size being less than that of flax seed. These 
grains are, however, never pure platinum, but generally 
contain palladium, and rhodium, iridium, and osmium, and 
sometimes gold, silver, lead, and titanium. 

These grains contain from 55 to 60 per cent of platinum. 
They are perfectly infusible by all common means, but in 
small quantities yield to the compound blow-pipe. The 
alloys of platinum must therefore be analyzed in the moist 
way, that is, by means of acids, and not by heat. 

TESTS FOR PLATINUM. 

The solutions of this metal in nitro-muriatic acid, it being 
msoluble in any other, are of a brownish yellow. 
Muriate of ammonia. Yellow precipitate, 
Muriate of tin, Bright red do. 

Alkalies, Yellow do 



ANALYSIS OF METALLIC SUBSTANCES. 419 



ASSAY OF PLATINUM. 

Process 1. — Digest a given quantity of grain platina, say 
100 grains, in a retort, with 10 times its weight of aqua- 
regia consisting of four parts of muriatic, with one part of 
nitric acid ; apply the heat of a lamp until one half the 
acid passes over into the receiver ; decant the fluid remain- 
ing in the retort, and repeat the process with a fresh quan- 
tity of acid as before, and if necessary a third time. There 
will now appear a dark colored powder at the bottom of the 
retort, being the insoluble matter the metal contained, while 
the platina will be in solution. This must now be thrown 
on a filter, and washed with pure water. 

Process 2. — The solution of platina, which is of a brown 
color, must next be treated with solution of muriate of am- 
monia, which will precipitate the metal in form of a yellow 
oxide, and this must be collected, washed and dried. 

Process 3. — The dried precipitate of the last process, is 
to be heated in a crucible until all fumes cease, when 
there will remain a spongy mass of platina, the weight of 
which will show the per centage of the metal in the quan- 
tity assayed. Thus, of the 100 grains, if 55 grains remain, 
it shows 55 per cent., the rest being oxygen. 

This, it will be seen, does not show the exact analysis of 
the metal, but only the quantity of platina it contained. In 
order to obtain the number, and precise quantity of the dif- 
ferent substances which grain platina contains, requires a 
much more extended analysis, and which can only be made 
by those who have had much experience, and possess great 
skill in chemical manipulations. It is therefore hardly 
necessary to describe here, the various and complicated 
processes by which it is done. 

MALLEABLE PLATINA. 

Platina, being the most infusible of the metals, and at 
the same time not oxydable by exposure, or by heat, and 
being soluble only in nitro-muriatic acid, it is therefore one 
of the most perfect of metallic substances. For many uses 
in the arts, it is superior to gold itself, and for others, as 
chemical vessels, no other substance can take its place. It 
would therefore come into general use for a great variety of 
purposes, did not its high price keep it among the more 
rare and precious metals. The quantity in which this metal 
exists, nor the difficulty of obtaining it, are the reasons for 



420 ANALYSIS OF METALLIC SUBSTANCES. 

this scarcity, but the labor and expense of purifying', so as 
to render it a malleable metal. Like iron, it can be welded, 
which property exists in no other metals, but for this pur- 
pose It passes through a variety of processes, of which the 
following are descriptijDns : 

First. — Precipitate the platina from its solution, by the 
muriate of ammonia, and reduce it by heat in a crucible, to 
"he spongy metalhc texture, the several processes of doing 
which, are already described above, under the article " as- 
say," and which it is not necessary here to repeat. 

Second. — To one part of this spongy metal, add two 
parts of mercury, and with a pestle amalgamate them in 
a glass mortar. This is readily done, the two metals 
having a strong affinity to each other. Where considera- 
ble quantities are to be amalgamated, small parcels of each 
are to be done at a time, the best method of conducting it 
being to combine about two drachms of mercury to three of 
the platina, and having made the union perfect, by rubbing 
with the pestle, add to this small quantities of each, until 
the whole is united. 

Third. — When the whole quantity is amalgamated, it is 
to bo compressed into tubes of hard wood, by m^eans of an 
iron screw, the pressure of which is against a cylinder of 
wood, adapted to the bore of the tube. By this means 
the mercury of the amalgam is forced out, and the parti- 
cles of the platina are brought together so as to make a solid 
mass. 

Fourth. — After the metal has remained underpressure, as 
above described, for two or three hours, place the tube of 
wood containing the platina on charcoal, in a smith's forge, 
or in a crucible lined with charcoal, and after the wood is 
burned away, urge the fire to the highest possible degree of 
whiteness, after which, the cylinder of platina may be taken 
out of the fire, and while white with heat, hammered lightly 
for a moment, and then returned to the fire again, prepara- 
tory to the repetition of the same process. The metal now 
becomes solid, and fit to be forged, or drawn into wire. If, 
however, it has not been well purified from the osmium, 
iridium, and other metals which crude platina usually con 
tains, it will break under the hammer, and never can be 
made malleable. The only remedy for this evil, is to re- 
dissolve the whole in nitro-muriatic acid, and repeat the 
several processes as already described. 



ANALYSIS OF METALLIC SUBSTANCES. 421 

MOLVBDENUM. 

This metal is obtained in its pure state with considerable 
difficulty, and when thus obtained, is not applied to any 
useful purpose. Its ores are few in number, and exist only 
in small quantities at a place. 

Sulphuret of molybdena, Molybdena and sulphur. 
Oxide of molybdena, Molybdena and oxygen. 

Molybdate of lead, Molybdic acid and lead. 

ACTION OF THE BLOW-PIPE, 

When the native sulphuret of molybdena is exposed to 
the action of the blow-pipe, sulphurous vapors in the first 
place are emitted, and afterwards, if the heat be urged, 
white fumes arise, being an oxide of the metal. By means 
of nitric acid, this metal is converted into molybdic acid. 

TESTS OF SOLUTIONS OF MOLYBDENA. 

The molybdic acid forms soluble salts with soda, potash, 
and ammonia. The solution of molybdic acid, in sulphuric 
acid, is of a blue color when cold, changing to white when 
heated, and to blue again when cooled. The molybdates of 
potash and soda give precipitates with almost every me- 
tallic solution. 

Muriate of gold. White powder. 

Muriate of mercury, White do. 

Muriate of tin. Blue do. 

Muriate of cobalt. Rose colored do. 

ASSAY OF THE ORES OF MOLYBDENA. 

The method of assaying the sulphuret of molybdena is 
very simple. It is first digested in nitric acid with heat ; 
this will form molybdic acid, which will remain in solution, 
while the sulphur will be left behind. After filtration, the 
solution is to be evaporated to dryness, when molybdic acid 
will be the result. 

MANGANESE. 

The ores of this metal are quite common, and in some 
instances it is found in large quantities, though more fre- 
quently it occurs with the ores of other metals, of which it 
forms a small portion. The following are the most common 
ores of manganese : 



422 ANALYSIS OF -METALLIC SUBSTANCES. 

Black oxide of manganese. \ Manganese, oxygen 

* I and water. 

SiUciferous oxide of manganese, ^^^^^'lex °''^^^'' 
Sulphuret of manganese, Manganese and sulphur. 

Phosphorate of manganese, \ Piio^Phonc acid and 

^ ( manganese. 

ACTION OF THE BLOW. PIPE ON MANGANESE. 

Heat alone on the oxides of this metal, produces little 
effect. With borax they form a beautiful violet colored 
glass, which is always a good test of the presence of this 
metal 

When the metal is in solution with muriatic acid, the 
alkalies throw down a white precipitate, which turns black 
on exposure to the air. 



Process 1. — Dissolve the black oxide in muriatic acid, 
which will also take up the iron with which it is usually 
mixed: add caustic ammonia in excess; this will throw 
down the oxide of iron, leaving the manganese in solution, 
which is then to be obtained, by evaporating to dryness, and 
exposure to a red heat. 

Process 2. — The pure oxide thus obtained is to be mixed 
into a paste with linseed oil, and a little charcoal, and sub- 
mitted, in a crucible, to the most violent heat that can be 
raised, for an hour or more, when, if the experiment is well 
performed, a button of the metal will be found at the bot- 
tom. This is of an iron gray color, is magnetic, hard and 
brittle, and soon tarnishes on exposure to the air. Metalhc 
manganese has not been applied to any use. It is, however, 
of considerable consequence in the form of the native oxide, 
as being the substance from which oxygen is obtained fo 
bleaching, ptud other purposes. 



INDEX. 



Page. 

Acetates 332 

Acetate of copper .... 333 

of lead 332 

Acid, acetic 332 

antimonious .... 282 

arsenious 278 

boracic 185 

carbo-sulphuric . . 219 

carbonic 171 

chloric 186 

chloriodic 194 

chromic 279 

citric 336 

columbic 282 

fluoboric 199 

fluoric 197 

fluosilisic 200 

hydrocyanic . . . 215 
hydrobromic . . . .318 
hydrochloric . . . 188 

hydriodic 195 

hydrofluoric . . . 318 
hydroselenic .... 318 
hydrosulphuric . . 318 
hydroferrocyanic . . 319 
hydronitric .... 167 

iodic 194 

meconic 355 

molybdic . ... 280 



Pagt, 

Acid, muriatic 189 

nitric 166 

nitrous 165 

nitro-hydro chloric . . 144 
nitro-muriatic . . . 144 
oxymuriatic .... 186 
oxalic ...:.. 333 
phosphoric .... 184 
phosphorous . . . 185 

prussic 215 

pyroligneous . . . 332 

of sorrel 333 

sulphurous .... 178 

sulphuric 179 

tannic 341 

tartaric 334 

tungstic 281 

vanadic 293 

vegetable 331 

Action 50 

mechanical ... 50 

vital 49 

Agents, imponderable . . 10, 55 

Air, atmospheric .... 157 

condensation of . . . 38 

thermometer .... 41 

inflammable .... 200 

Affinity 81 

chemical .... 81 



INDEX. 



Pag-e. 

Affinity, double elective . . 85 
elective .... 83 

simple 83 

Alabaster 300 

Albumen 359 

Alcohol 347 

without distillation . 350 
in wines .... 351 

Alembic 115 

Alkali, volatile 168 

Alkaloids 354 

Allanite 284 

Alloys 228 

Alum 264, 301 

Alumina 264 

Amalgams 231 

Ammonia 168 

liquid .... 169 

muriate of . 169, 315 

nitrate of . . . 306 

Analysis of vegetables . . 328 

minerals . . . 371 

waters . . . 378 

Animal chemistry .... 358 

Anhydrous acid .... 180 

salts 296 

Animals resist heat ... 22 

Animal oils 360 

heat 365 

Antimony 282 

oxides of . . . 282 

sulphuret of . . 283 

tartrate of . . . 283 

Aphlogistic lamp .... 240 

Apparatus, chemical . . . 113 

for gas .... 117 

Aqua fortis 166 

regia 237 

Aqueous fusion .... 296 

Arrow root 338 

Arsenic 277 

oxide of 277 

sulphuret of . . . 278 
test of 277 



Arsenic, white 278 

Arseniates 278 

Atmospheric air ... . 157 
composition of 158 
carbonic acid in 158 

Atomic theory Ill 

Attraction 80 

of cohesion ... 80 

chemical ... 81 

of gravitation . 80 

Azote 154 

Balance, portable . . . .121 

Balloons 142 

Barium 252 

protoxide of . - . 253 

Barytes 253 

muriate of . . . 316 
Barley, malting of ... . 354 
Barometer, thermometric . 18 

Bell-glass 120 

Bismuth 286 

oxide of .... 287 
flowers of . . . 287 
magistery of . . . 287 

Black lead 272 

Black oxide of manganese . 268 
Bleaching powder . ... 188 

Blende 273 

Blood 360 

Bloodstone 271 

Blowpipe, common . . . 115 
Gahn's .... 116 
compound . . . 149 

use of 150 

Blue, Prussian 215 

Bodies, elementary .... 108 

ponderable . . . 130 

imponderable ... 10 

Boiling of liquids .... 18 

Borates 1S5, 311 

Borate of soda 311 

Borax .185 

Boron 185 



INDEX. 



Brass 
Bromine 



Cadmium 

Calamine 

Calcimn 

oxide of . . 

Calomel 

Caloric 

conductors of . 
combined .' . 
equilibrium of 
expansion of 
latent in steam 
specific . . 
reflection of . 
sources of 
of fluidity . . 
capacity for . 
transmission of 
Canton's phosphorus 
Caoutchouc .... 

Carbon 

and oxygen . . 
sulphuret of . 
Carbonic acid . . . 
poison . . 
oxide . . . 
properties of 
Carbonates .... 
of soda . 
of potash . 
of lead . 

Caflfeiu 

Calico-printing . . . 
Carbo- sulphuric acid . 
Carburetted hydrogen 
light . . 
Caustic, lunar . . . 

Cerium 

Cistern, pneumatic . 

Chemical affinity . . . 

force of 

combinations . 



Page. 

273 
196 

274 

273 

254 

255 

233 

11 

23 

13 

13 

25 

16 

35 

30 

48 

13 

16 

33 

53 

355 

170 

171 

219 

171 

174 

176 

173 

313 

314 

313 

291 

340 

219 

200 

200 

235 

284 

151 

81 

94 

90 



Fag*. 

Chemical apparatus . . . 113 
equivalents . . . 104 
symbols . . . 127 
Chemistry defined .... 9 
inorganic . . . 133 
organic .... 319 
of mineralogy . 371 

Chlorates ^88,307 

Chlorate of potash ... 308 

Chlorides 188 

Chloride of nitrogen ... 193 
calciimi . . . 258 
sodium . . . 250 

lime 256 

tests for . 260 

Chlorine 186 

how prepared . . 186 
supports combustion 187 
metals bum in it . 187 
oxides of . . . 190 
and oxygen . . .190 
and sulphur . . 190 
and nitrogen . . . 193 
Chloruret of sulphur . . . 190 

Chromium 279 

Chromate of lead .... 280 

iron .... 279 

Chrome, analysis of . . . 415 

Chrome yellow 280 

Cinchonia 356 

Cinnabar 234 

Class ii 244 

Classification of metals . . 109 
Citric acid ...... 336 

Coal gas 208 

Cobalt 284 

analysis of ... . 395 
oxides of ... . 285 
arsenical ..... 284 

Coffee 

Codeia d55 

Cohesion 87 

Cohesion, attraction of . . 87 
Cold, artificial 16 



INDEX 



Page. 



of the blood . 


. 360 


art of ... . 


. 340 


Colors, primary . . . 


. 51 


Colmnbium 


. 281 


Combination .... 


. 102 


by volume . 


. 103 


Common salt .... 


, 250 


Compoimd blow-pipe . . 


. 149 


Combining proportions . 


. 102 


Combined caloric . . . 


. 13 


Combustion 


. 48 


what . . . 


. 136 


changes by . 


. 138 


m oxygen . 


. 137 


of hydrogen 


. 147 


loss of weight 


by 139 


of iron . . 


. 137 


spontaneous 


. 342 


of zinc . . 


. 138 


Conductors of caloric . . 


. 23 


Concave mirrors . . . 


. 30 


Copper 


. 288 


protoxide of . . 


. 289 


peroxide of . . . 


. 290 


sulphate of . . 


. 289 


sulphuret of . 


. 290 


reduction of . . 


. 290 


tests for . . . 


. 403 


sesquioxide of . 


. 127 


Copperas ] 


[80, 303 


Corrosive sublimate . . 


. 233 


Cotyledon 


. 322 


Cream of tartar . . . 


. 334 


Cryophorus 


. 21 


Crucible 


. 113 


Crystalization . . . 


. 295 


water of . 


. 295 


Cupellation .... 


. 384 


Cup, galvanic .... 


. 68 


Cyanogen 


. 214 


Cyanuret of mercury 


. 214 



Decomposition, double . . 86 



PaffOo 

Deutoxide of hydrogen . . 153 

lead .... 292 

Definite proportions ... 97 

Decrepitation 296 

Derbyshire spar .... 312 

Density of air 39 

Didymium 284 

Double salts .... 297, 335 
Destructive distillation . 237, 329 
Diamond, burning of . . .170 
Difierential thermometer . 41 

Dropping tube 116 

Diana's silver tree . . . 235 

Dolomite 53 

Dutch gold 289 

Dying, art of 341 

Earths 262 

metallic bases of . . 262 

properties of . . . 264 

Ebullition, cause of. . . . 16 

Efflorescence 296 

Elatin 

Elasticity in affinity ... 89 

Elective affinity 83 

double . . 85 

Electrical pile 34 

Electricity 55, 57 

conductors of . . 60 
theory of . . . 58 
magnato ... 62 
chemical, effects of, 60 
Electro-chemical theory . . 75 
Electro-magnetism ... 78 

Elements 108 

their number . . 108 

Emetia 358 

Emetic tartar 283 

Epsom salt 301 

Equivalents, chemical . . 108 
Equivalent numbers . . . 108 
table of 124 
Essential organs of plants . 322 
Esseatial oils 343 



INDEX. 





Page. 


Essential oils, table of . 


. 343 


Ether 


. 35-2 


evaporation of . . 


. 353 


Etching on glass . . . 


. 198 


Endiometry 


. 164 


Extractive matter . . . 


. 340 


Expansion by heat . . 


. 25 


of solids . . 


. 26 


of liquids 


. 29 


of gases . . 


. 26 


Evaporation 


. 19 


freezing by 


. 21 


Evaporating dish . . . 


. 115 



Fermentation 345 

saccharine . 345 
vinous . 345, 349 

Felling colliery 202 

Fibrin 358 

Fire-damp 201 

Fixed air 171 

Fixed oils 342 

Florence flask 115 

Friction matches .... 310 

causes heat ... 50 
Flowers of sulphur . . .178 

of zinc .... 274 
Fluidity, caloric of . . . . 13 

Fluoboric acid 199 

Fluor spar .... 197, 312 

Fluoric acid 197 

Fluorine 199 

Fluosilisic acid .... 200 
Fulminating powder . . . 306 

Food of plants 323 

Freezing mixture .... 46 
Fluate of lime .... 197, 312 
Fowler's solution .... 278 

Fusible alloy 228 

Furnace lamp 119 

Galena 292 

Galvanic battery .... 65, 68 
circle .... 64 
trough 68 



Galvanic poles . > . . . 66 
cups . . . . 68, 73 

pile 65 

Galvanism 62 

chemical effects of 70 
theory of . . . 75 
heating effects of 78 
discovery of . . 63 

Galvanometer 69 

Gases, by volume .... 103 
expand equally . . 28 
their weight . . . 123 
liquefaction of . . . 43 

Gas, oxygen 133 

hydrogen 140 

carbonic acid . . 45, 171 

chloric 186 

muriatic acid . . . 189 

fluoric acid 197 

Hghts 208 

oil 209 

oleaant 209 

nitrogen 154 

nitrous oxide ... 161 

portable 210 

apparatus 117 

Gelatine 359 

Gentianin :...... 359 

Germination of seeds . . . 323 

Gilding 238 

Glass 267 

Glauber's salt 298 

Glucina 265 

Gluten 339 

Gold 236 

analysis of .... 388 
malleability of . . .237 
solution of .... 237 
gilding with .... 238 

Gravitation 80 

Gravity, specific . . . . . 120 

in affinity ... 90 

Growth of plants .... 324 

Green vitriol 303 

Gunpowder 305 



INDEX. 



Gypsum 297 

Gums . i 337 

Hartshorn 168 

Heavy spar 299 

Heat 11, 87 

animal 365 

latent 13 

expansion by .... 25 

matter of 11 

radiation of .... 29 
resisted by animals . 22 

Hematite, red 271 

Hydriodate of potash . . 195 

Hydriodic acid 195 

Hydrochloric acid . . . 188 

Hydrogen 140 

and nitrogen . . 168 
carburetted . . 200 
how obtained . 141 
protoxide of . . 146 
and sulphur . . 212 
and phosphorus . 213 
action on platina 144 
sulphuretted . .212 
phosphuretted . 2 3 
precipitates gold . £ 7 

Hydrocyanites 2l8 

Hydrosulphuret of potash . 317 

Hydrochlorates 189 

Hyperoxymuriates .... 188 
Hydracids, salts of . . . 318 

Ice cream 46 

Imponderable agents . . 10, 55 

Ink 307 

indelible 307 

sympathetic .... 285 
Ingredients of plants . , . 336 
Inorganic chemistry . . . 133 

Iodides 194 

Iodine 193 

Iodic acid 194 

Iodine and hydrogen . . . 195 

Iridium 243 

Iron 269 



Page. 

Iron, combustion of. . . . 137 

carburet of 272 

meteoric 270 

oxides of 271 

sulphate of . . . 180, 303 
sulphuret of ... . 272 

test of 412 

reduction of . . . . 414 

tinned 275 

Isinglass 359 

Ivory, silvering 236 

Kelp 314 

King's yellow 278 

Lamp furnace 119 

flameless 210 

safety 206 

Lantanum 284 

Laws of combination . 100 
of proportion ... 97 

Lead 290 

acetate of 332 

analysis of ... . 402 

oxides of 291 

sulphuret of ... . 292 

poisonous 291 

white 291 

sugar of 332 

Lemon, salts of 336 

Liquid ammonia 169 

phosphorus . . . 183 
Liquefaction of the gases . 43 

Light 51 

decomposition of . . 51 
without heat ... 53 
effects on colors . . 54 
on crystalization . . 55 
Light carburetted hydrogen . 200 

Lime 254 

chloride of 256 

phosphate of. . . . 183 
phosphuret of . . . . 261 
carbonate of ... 255 
and chlorine .... 256 
I sulphate of .... 300 



INDEX. 



Pa^e, 

Lime water 256 | 

Liquid phosphoras . . . 183 j 
Liquids expand by heat . . 28 
conductors of heat 24 

Litharge 291 

Lithium 252 

Looking-glasses, silvering . 231 
Lunar caustic . . . 235, 306 

Magnetism, electro ... 78 

Magnesia 264 

sulphate of . . . 301 
Maximum density ... 39 

Manganese 268 

oxide of ... 268 
assay of . . . 422 

Massicot 291 

Matrass 114 

Meconia 355 

Meconic acid 355 

Molasses . 337 

Mercury 230 

peroxide of . . . 232 

protochloride of . . 233 

sulplmret of . 230, 234 

Metallic compounds . . . 228 

alloys 228 

salts 228 

Metals 222 

arrangement of . . 229 
combustible . . . 225 
combine with sulphur 227 
discovery of . . . 222 
classification of . . 229 
become oxides . . 224 
general properties of 223 
how reduced . . . 225 
positive electrics . 223 

Class i 229 

Meteoric iron 270 

Mineralogy, chemical . . . 383 

Mineral green 289 

Mineral waters 379 

analysis of . 378 
Mirrors, concave .... 30 



Molybdic acid 280 

Molybdenum 280 

tests ... 421 

Mordant 341 

Morphia 355 

Muffle 385 

Multiple proportions ... 99 

Muriates 189,315 

Muriatic acid 189 

Musical tones 143 

Muriate of ammonia . . 315 
of barytes .... 316 

Narcotine 355, 356 

Narceia 255 

Nickel 286 

Nicholson's balance . . . 121 

Nitrates 304 

Nitrate of potash .... 304 

Nitric acid 166 

anhydrous .... 167 

oxide 163 

Nitre 166 

Nitrous acid 165 

oxide 161 

gas 163 

Nitrogen 154 



carburet of . . 


. 214 


chloride of . . 


. 193 


binoxide of . . 


. 163 


and hydrogen . 


. 168 


and oxygen . . 


. 160 


Nomenclature .... 


. 125 


Non-metallic bodies . . 


. 133 



Oil of turpentine .... 344 

Oil gas 211 

Oil of-\itriol 179 

Oils, vegetable 342 

fixed 342 

Olefiant gas 207 

Opium 355 

Organic chemistry . . . 319 

Orpiment 278 

Osmium 243 



INDEX. 



Page, 

Oxalates 334 

Oxides, metallic .... 224 

Oxidation 225 

Oxygen gas 133 

consumption of . .159 

how obtained . . 133 

combustion of . . 137 

affinity of . . . . 135 

Oxymuriatic acid .... 186 

Oxymuriate of potash . . 308 

Oxygenized water ... . .153 

Oxygen and hydrogen . . 155 

Palladium 242 

Pearl-ash 313 

Phosphates .... 184,310 
Phosphate of soda . . . 311 

Photometer 52 

Phosphorus 182 

and oxygen , .184 

Phosphites 185 

Phosphorescence .... 53 
Phosphuretted hydrogen . 213 

Pile of Volta 65 

Plants, growth of ... . 324 

food of 323 

ingredients of . . 336 
■Plaister of Paris .... 300 

Platinum 238 

assay of ... . 419 
action on hydrogen 144 
malleable . . .239 
peroxide of . . . 242 
protoxide of . . . 242 
sponge .... 144 
Pneumatic cistern .... 151 

Plumbago 272 

Ponderable bodies .... 130 

Portable gas 210 

Potassa 245 

Potassium 245 

protoxide of . . 247 

and oxygen . . 247 

oxide of ... . 245 

Potatoe starch 338 



Potash, chlorate of ... . 303 
hydriodate of . . . 195 

Pot, melting 113 

Proportions, definite ... 97 
indefinite . . 95 
by volume . . 102 
multiple ... 99 
how known . 106 

Prussian blue 215 

Prussic acid 215 

deadly poison . 217 

Pyrites 272 

Pyrometer 26 

Pyrophorus, Romberg's . 302 

GLuicklime 255 

Q.uicksilver 230 

Cluinia 355,357 

sulphate of ... . 357 

Radiant heat 29 

Realger 278 

Red oxide of copper . . . 290 

lead 291 

precipitate .... 232 

Reduction of metals . . . 225 

Reflectors 30 

Resins 344 

Respiration 361 

Receiver 114 

Retort 114 

Rhodium 242 

Roasting ores 384 

Rust of iron 271 

Saccharine fermentation . . 345 
Salts of the hydracids . . 318 

Safety lamp 206 

Sal-ammoniac .... 164, 315 

Salafiable base 294 

Sa.lt, common 250 

of sorrel 333 

of lemons . . . 334, 336 

Salts 293 

remarks on ... . 294 
nomenclature of , . . 125 



INDEX. 



Sap of plants 332 

Scale of equivalents . . .110 
Sealing vr&x ....... 345 

Serum 360 

SiUca 266 

Silicium 266 

iSilver 234 

analysis of ... . 390 
antimonial . . . 389, 391 
muriate of .... 391 
nitrate of .... 306 

solvent of 236 

Silvering powder .... 235 

ivory 236 

looking-glasses . 231 

simple bodies . . 108 

what 130 

No. 131 

Smalt 285 

Soda 249 

muriate of .... 250 
phosphate of . . , .311 

borate of 185 

sulphate of 298 

Sodium 249 

protoxide of . . . 249 
chloride of ... 250 

Solar spectrum 51 

phosphori 299 

Solids expand by heat . . 26 

Solution 88 

Sources of caloric ... 48 

Spar, Derbyshire . . 197, 312 

heavy .... 253, 299 

Specific gravity .... 120 

how taken . 121 

of solids . 121 

of liquids . 121 

of gases . 122 

Spiritous liquors 348 

Starch 338 

Steam 15 

latent heat of . . . 16 

Steel 270 

Strontia 254 





Page. 


Strontia protoxide of . 


. . 254 


Strychnia 


. . 357 


Sugar 


. . 337 


how made . . 


. . 337 


beet ..... 


. . 337 


maple . . . 


. . 337 


of lead. . . . 


. . 332 


Sulphates 


. . 297 


of copper . 


. . 403 


of potash . 


. . 297 


alumina . . 


. . 301 


baryta . . 


. . 299 


magnesia . 


. . 301 


iron . . . 


. . 303 


zinc . . . 


. . 303 


Sulphur 


. 177 


and hydrogen . 


. . 212 


and oxygen . 


. 178 


and chlorine . 


. . 190 


chloruret of . 


. . 190 


Sulphurets 


. . 177 


of lead . . 


• 292 


of copper . 


. . 290 


of iron . . 


. 272 


of mercury . 


. . 230 


Sulphurous acid . . 


. 178 


Sulphuric acid . . . 


. . 179 


Sulphuretted hydrogen 


. 212 


Supporters of combustio 


n . 131 


Synthesis, chemical . 


. 9 


Symbols, chemical . . 


. . 127 


table of . . 


. 128 


Table of equivalents . 


108, 124 


of metals . . 


. 222 


of elements . . 


. . 108 


Tannin - . 


. 341 


Tannic acid .... 


. . 342 


Tapioca 


. 339 


Tartar emetic . . . 


283, 335 


Tartar, cream of . . . 


. 334 


Tartaric acid .... 


. . 334 


Tellurium , . . . . 


. 288 


Temperature, animal . 


22, 365 


Theory of galvanism . 


. 75 



INDEX. 



Pa^e. 

Thermometer 40 

air ... . 41 
construction of 41 
differential . 41 
Fahrenheit's . 43 
Thermo-electrical pile . , 34 

Tin 275 

its uses 275 

oxides of 276 

Titanium 287 

Tones, musical 143 

Transmission of heat . . 33 
Trough, galvanic .... 68 
Triphosphuret of copper . 127 

Triple salts 297 

Tungsten 281 

Tungstic acid 281 

Turpentine, oil of . . . . 344 

Uranium 283 

Vanadium 293 

Vanadiates 293 

Vapor 38 

Vaporization 38 

Van Helmont's willow . . 324 

Vegetation 322 

Vegetable acids .... 331 
alkaloids . . . 354 

oils 342 

alkaloids . . . 354 
oils .''\ . . . 342 
alkalies .... 354 
chemistry . . . 321 
Vegetables, analysis of . . 328 
Ultimate princip. 330 

Verdigris 289,333 

Veratria 357 

Verditer 289 

Vermillion 234 

Vinegar 332 

Vinous fermentation . . . 345 



Vital action 49 

Vitriol blue 403 

green 303 

white 303 

Volumes, theory of . . . 103 

Volta's pile 65 

Volatile salts 170 

Volatile oils 342 

Water 146 

analysis of . . . 148 
absorbs gases . . .153 
contains air ... 153 
of crystaUzation . . 295 
decomposition of . 148 
properties of . . . 151 
oxygenized . . . 153 
expands in freezing . 152 

boiling 18 

s}Tithesis of . . . .147 
weight of .... 151 

Wheat 3our 339 

Wells, caution about . . 140 

White arsenic 278 

White vitriol 303 

Wines, alcohol in ... . 351 
Wollaston's scale .... 109 
Wolfram 281 

Yttria 265 

Zinc 273 

aUoysof 273 

combustion of . . . .138 
analysis of .... 409 
flowers of . .... 274 

oxides of 274 

reduction of .... 273 
sulphat.; of .... 303 

Zafii-ee 285 

Zirconia 265 

Zero 43 



^ 



